Pin sketch compilation actions to major version refs

Previously, the development versions of Arduino's sketch compilation actions were used in the project's GitHub Actions
workflows. Using release versions of the actions instead provides a more stable CI system.

Use of the major version ref will cause the workflow to benefit from ongoing development to the action up until such
time as a new major release is made, at which time we would need to evaluate whether any changes to the workflow are
required by the breaking change that triggered the major release before updating the major ref
(e.g., `uses: arduino/compile-sketches@v1` -> `uses: arduino/compile-sketches@v2`).

Author: per1234

.github/workflows/compile-examples.yml

@@ -122,7 +122,7 @@ jobs:
         run: tree extras/
 
       - name: Compile examples
-        uses: arduino/compile-sketches@main
+        uses: arduino/compile-sketches@v1
         with:
           fqbn: ${{ matrix.board.fqbn }}
           libraries: |

.github/workflows/report-size-deltas.yml

@@ -10,4 +10,4 @@ jobs:
 
     steps:
       - name: Comment size deltas reports to PRs
-        uses: arduino/report-size-deltas@main
+        uses: arduino/report-size-deltas@v1