dockerfile: fix gpac version to 2.4.0 (#1747)

GPAC renamed its libraries to `libgpac.so.13` causing image build  to fail:

```
Error: building at STEP "COPY --from=builder /usr/local/lib/libgpac.so.12 /usr/local/lib/": checking on sources under "/home/pszemus/.local/share/containers/storage/overlay/faa4f2b5c39251a5cf42a97234d2d5652336a2388c96a64d85fc1922c4c43a71/merged": copier: stat: "/usr/local/lib/libgpac.so.12": no such file or directory
```
so let's fix the gpac version to the latest release (2.4.0)

Author: pszemus

docker/dockerfile

@@ -7,7 +7,7 @@ RUN apk add --no-cache --update git curl gcc cmake glew glfw \
   zlib-dev libpng-dev libjpeg-turbo-dev openssl-dev freetype-dev libxml2-dev bash cargo
 
 WORKDIR /root
-RUN git clone https://github.com/gpac/gpac 
+RUN git clone -b v2.4.0 https://github.com/gpac/gpac
 WORKDIR /root/gpac/
 RUN ./configure && make -j$(nproc) && make install-lib
 WORKDIR /root 
@@ -43,4 +43,4 @@ COPY --from=builder /usr/lib/libsharpyuv.so.0 /usr/lib/
 
 COPY --from=builder /ccextractor /
 
-ENTRYPOINT [ "/ccextractor" ]
+ENTRYPOINT [ "/ccextractor" ]