checks the compatibility of the licenses (#2844)

# Description of Changes

### What was changed
- An **automated license check** was integrated into the CI/CD workflow
(`build.yml` and `licenses-update.yml`).
- A new file, `allowed-licenses.json`, was added to explicitly define
the permitted licenses.
- The **Gradle build process** was updated to run `checkLicense` and
detect any non-compliant licenses.

### Why the change was made
- **Improved license compliance** to ensure only compatible licenses are
used.
- **Automated license validation** within the CI/CD workflow to detect
potential incompatibilities early.
- **Legal risk mitigation** by excluding problematic licenses like
**GPL-2.0 (without Classpath Exception)**.

### Any challenges encountered
- The **allowed license list had to be manually curated** to ensure all
relevant open-source libraries were covered.
- Some dependencies use **slightly different license names** (e.g.,
`"Apache License, Version 2.0"` vs. `"Apache-2.0"`), which needed to be
handled in the validation process.

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [x] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] My changes generate no new warnings

### Documentation

- [x] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [x] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#6-testing)
for more details.

.github/workflows/build.yml

@@ -64,6 +64,35 @@ jobs:
             build/reports/problems/
           retention-days: 3
 
+  check-licence:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@cb605e52c26070c328afc4562f0b4ada7618a84e # v2.10.4
+        with:
+          egress-policy: audit
+
+      - name: Checkout repository
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@3a4f6e1af504cf6a31855fa899c6aa5355ba6c12 # v4.7.0
+        with:
+          java-version: "17"
+          distribution: "adopt"
+
+      - name: check the licenses for compatibility
+        run: ./gradlew clean checkLicense
+
+      - name: FAILED - check the licenses for compatibility
+        if: failure()
+        uses: actions/upload-artifact@65c4c4a1ddee5b72f698fdd19549f0f0fb45cf08 # v4.6.0
+        with:
+          name: dependencies-without-allowed-license.json
+          path: |
+            build/reports/dependency-license/dependencies-without-allowed-license.json
+          retention-days: 3
+
   docker-compose-tests:
     # if: github.event_name == 'push' && github.ref == 'refs/heads/main' ||
     #     (github.event_name == 'pull_request' &&

.github/workflows/licenses-update.yml

@@ -28,7 +28,7 @@ jobs:
         with:
           app-id: ${{ secrets.GH_APP_ID }}
           private-key: ${{ secrets.GH_APP_PRIVATE_KEY }}
-          
+
       - name: Check out code
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
@@ -40,8 +40,17 @@ jobs:
 
       - uses: gradle/actions/setup-gradle@0bdd871935719febd78681f197cd39af5b6e16a6 # v4.2.2
 
-      - name: Run Gradle Command
-        run: ./gradlew clean generateLicenseReport
+      - name: check the licenses for compatibility
+        run: ./gradlew clean checkLicense
+
+      - name: FAILED - check the licenses for compatibility
+        if: failure()
+        uses: actions/upload-artifact@65c4c4a1ddee5b72f698fdd19549f0f0fb45cf08 # v4.6.0
+        with:
+          name: dependencies-without-allowed-license.json
+          path: |
+            build/reports/dependency-license/dependencies-without-allowed-license.json
+          retention-days: 3
 
       - name: Move and Rename License File
         run: |