Add: Convert PDF to WebP (#1666)

* Add PDF to WebP

* add swagger param

* back

* creates a custom image for Docker from pymupdf

* Converting with pdf2image and Pillow instead of pymupdf

* webp remove to pdf-to-img

* remove mupdf

src/main/java/stirling/software/SPDF/model/api/converters/ConvertToImageRequest.java

@@ -12,7 +12,7 @@ public class ConvertToImageRequest extends PDFFile {
 
     @Schema(
             description = "The output image format",
-            allowableValues = {"png", "jpeg", "jpg", "gif"})
+            allowableValues = {"png", "jpeg", "jpg", "gif", "webp"})
     private String imageFormat;
 
     @Schema(