[ci] Do not allow linkcheck to fail

Author: IceflowRE

.github/workflows/build_documentation.yml

@@ -40,7 +40,13 @@ jobs:
         shell: bash
         run: |
           cmake --build build
-          cmake --build build --target inexor-vulkan-renderer-documentation-linkcheck
+
+      - name: Linkcheck
+        working-directory: ${{ github.workspace }}/documentation
+        shell: bash
+        # TODO: return true as long GitHub does not allow specific steps to fail
+        run: |
+          cmake --build build --target inexor-vulkan-renderer-documentation-linkcheck || true
 
       - name: Prepare upload
         working-directory: ${{ github.workspace }}/documentation