Attempt to fix Doxygen action

.github/workflows/doxygen.yml

@@ -13,7 +13,7 @@ jobs:
     - uses: actions/checkout@v2
         
     - name: Doxygen Action
-      uses: mattnotmitt/doxygen-action@v1
+      uses: mattnotmitt/doxygen-action@v1.9.2
       with:
         doxyfile-path: "./Doxyfile"
         working-directory: "."