just copy bin and use it locally

.readthedocs.yaml

@@ -22,8 +22,7 @@ build:
       curl -L https://sourceforge.net/projects/doxygen/files/rel-$DOXYGEN_VERSION/doxygen-$DOXYGEN_VERSION.linux.bin.tar.gz > doxygen.tar.gz &&
       gunzip doxygen.tar.gz &&
       tar xf doxygen.tar &&
-      cd doxygen-$DOXYGEN_VERSION &&
-      make install
+      mv doxygen-$DOXYGEN_VERSION/bin/doxygen ./
     # get lib version & overwrite Doxyfile values
     - >
       echo $(pwd) &&
@@ -32,7 +31,7 @@ build:
       echo "PROJECT_NUMBER = $RF24_VERSION" >> docs/doxygenAction &&
       echo -e "\n@INCLUDE = doxygenAction" >> docs/Doxyfile
     # run doxygen
-    - doxygen
+    - cd docs && ./.doxygen/doxygen
     # copy output to RTD output path for HTML files
     - mv docs/html/ "$READTHEDOCS_OUTPUT/"