reordered the actions, so clang-format and doxygen are run first

This change reorders the actions so the least expensive and most failing
actions are run first. On a typical run, doxygen and clang-format take
each about 2s (plus 7s install), the complete building on all the supported platforms
10 minutes. In my experience, the most fails I get are from formatting
and documentation errors, not from compilation problems. This gives the
users a much faster feedback on needed changes in their commits and PRs
and shaves off a lot of execution time.

Author: eringerli

example_actions.yml

@@ -19,14 +19,14 @@ jobs:
     - name: pre-install
       run: bash ci/actions_install.sh
 
-    - name: test platforms
-      run: python3 ci/build_platform.py main_platforms
-
     - name: clang
-      run: python3 ci/run-clang-format.py -e "ci/*" -e "bin/*" -r . 
+      run: python3 ci/run-clang-format.py -e "ci/*" -e "bin/*" -r .
 
     - name: doxygen
       env:
         GH_REPO_TOKEN: ${{ secrets.GH_REPO_TOKEN }}
         PRETTYNAME : "Adafruit Arduino Library"
       run: bash ci/doxy_gen_and_deploy.sh
+
+    - name: test platforms
+      run: python3 ci/build_platform.py main_platforms