Fixes AppImage CI

Update Librsvg to version v2.52.2 from source

.github/workflows/appimage.yml

@@ -48,6 +48,26 @@ jobs:
           echo "Building and installing."
           sudo make -j$(nproc) install
 
+      - name: Install Librsvg required min. version
+      # Required min. version is not available for Ubuntu 20.04 LTS (but is for 22.04 LTS) so needs to be built manually
+        run: |
+          LIBRSVG2_VERSION='2.52.2'
+          echo "Cloning Librsvg2 $LIBRSVG2_VERSION."
+          git clone --depth 1 --branch "$LIBRSVG2_VERSION" https://gitlab.gnome.org/GNOME/librsvg.git ext/librsvg2
+
+          echo "Installing required dependencies with apt."
+          DEBIAN_FRONTEND=noninteractive sudo apt install -y rustc cargo gtk-doc-tools libgirepository1.0-dev
+
+          echo "Updating PATH."
+          export PATH="$PATH:/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0"
+
+          echo "Configuring build."
+          cd ext/librsvg2
+          sh autogen.sh
+
+          echo "Building and installing."
+          sudo make install
+
       - name: Configure build
         run: |
           export REF_NAME_FILTERED="$(echo '${{github.ref_name}}' | sed 's/[^A-z0-9_.-]//g')"