Update action versions used in sketch compilation workflows

Previously, due to the lack of a release, the development versions of the sketch compilation actions were used. Using
release versions provides a more stable CI system for the ArduinoIoTCloud project.

Author: per1234

.github/workflows/compile-examples.yml

@@ -185,7 +185,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: arduino/ArduinoCore-mbed
-          # the arduino/actions/libraries/compile-examples action will install the platform from this path
+          # the arduino/compile-sketches action will install the platform from this path
           path: ${{ env.ARDUINOCORE_MBED_STAGING_PATH }}
 
       - name: Checkout ArduinoCore-API
@@ -207,7 +207,7 @@ jobs:
         run: pip3 install pyserial
 
       - name: Compile examples
-        uses: arduino/compile-sketches@main
+        uses: arduino/compile-sketches@v1
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           platforms: ${{ matrix.platforms }}
@@ -232,7 +232,7 @@ jobs:
 
       - name: Save memory usage change report as artifact
         if: github.event_name == 'pull_request'
-        uses: actions/upload-artifact@v1
+        uses: actions/upload-artifact@v2
         with:
           name: ${{ env.SKETCHES_REPORTS_PATH }}
           path: ${{ env.SKETCHES_REPORTS_PATH }}

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

@@ -8,7 +8,7 @@ jobs:
 
     steps:
       - name: Comment size deltas reports to PRs
-        uses: arduino/report-size-deltas@main
+        uses: arduino/report-size-deltas@v1
         with:
           # The name of the workflow artifact created by the "Compile Examples" workflow
           sketches-reports-source: sketches-reports