First take at migrating to github actions

Signed-off-by: Sara Damiano <sdamiano@stroudcenter.org>

.github/workflows/build_examples.yaml

@@ -0,0 +1,90 @@
+name: Build Examples
+
+# Triggers the workflow on push or pull request events
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    if: "!contains(github.event.head_commit.message, 'ci skip')"
+
+    strategy:
+      matrix:
+        example:
+          [
+            examples/BlynkClient,
+            examples/FileDownload,
+            examples/MqttClient,
+            examples/WebClient,
+            tools/AT_Debug,
+            tools/Diagnostics,
+            tools/FactoryReset,
+          ]
+        modem:
+          [
+            TINY_GSM_MODEM_A6,
+            TINY_GSM_MODEM_BG96,
+            TINY_GSM_MODEM_ESP8266,
+            TINY_GSM_MODEM_M95,
+            TINY_GSM_MODEM_M590,
+            TINY_GSM_MODEM_MC60,
+            TINY_GSM_MODEM_SIM800,
+            TINY_GSM_MODEM_SIM808,
+            TINY_GSM_MODEM_SIM5360,
+            TINY_GSM_MODEM_SIM7600,
+            TINY_GSM_MODEM_SIM7000,
+            TINY_GSM_MODEM_UBLOX,
+            TINY_GSM_MODEM_SARAR4,
+            TINY_GSM_MODEM_XBEE,
+            TINY_GSM_MODEM_SEQUANS_MONARCH,
+          ]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set variables
+        run: |
+          if [[ -z "${GITHUB_HEAD_REF}" ]]; then
+            echo "::debug::Push to commit ${GITHUB_SHA}"
+            echo "LIBRARY_INSTALL_SOURCE=https://github.com/${GITHUB_REPOSITORY}.git#${GITHUB_SHA}" >> $GITHUB_ENV
+          else
+            echo "::debug::Pull Request from the ${GITHUB_HEAD_REF} branch"
+            echo "LIBRARY_INSTALL_SOURCE=https://github.com/${GITHUB_REPOSITORY}.git#${GITHUB_HEAD_REF}" >> $GITHUB_ENV
+          fi
+
+      - name: Restore or Cache pip
+        uses: actions/cache@v2.1.4
+        with:
+          path: ~/.cache/pip
+          # if requirements.txt hasn't changed, then it will be a "cache hit" and pip will be restored
+          # if requirements.txt HAS changed, it will be a "cache miss" and a new cache of pip will be created if the job completes successfully
+          key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
+          restore-keys: ${{ runner.os }}-pip-
+
+      - name: Restore or Cache PlatformIO and Libraries
+        uses: actions/cache@v2.1.4
+        with:
+          path: ~/.platformio
+          # if nothing in the lock files has changed, then it will be a "cache hit" and pip will be restored
+          # otherwise, it will be a "cache miss" and a new cache of libraries will be created if the job completes successfully
+          key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
+
+      - name: Set up Python
+        uses: actions/setup-python@v2
+
+      # This should be pulled from cache, if there's not a new version
+      - name: Install PlatformIO
+        run: |
+          python -m pip install --upgrade pip
+          pip install --upgrade platformio
+
+      - name: Run PlatformIO
+        env:
+          PLATFORMIO_CI_SRC: ${{ matrix.example }}
+          TINYGSM_MODEM_TO_USE: ${{ matrix.modem }}
+        run: |
+          echo "${{ env.LIBRARY_INSTALL_SOURCE }}"
+          pio lib --global install ${{ env.LIBRARY_INSTALL_SOURCE }}
+          pio lib --global install 89 415 1202 1286
+          platformio ci --project-option='build_flags=-D ${{ env.TINYGSM_MODEM_TO_USE }}' --project-option='framework=arduino' --board=uno --board=leonardo --board=yun --board=megaatmega2560 --board=genuino101 --board=mkr1000USB --board=zero --board=teensy31 --board=bluepill_f103c8 --board=uno_pic32 --board=esp01 --board=nodemcuv2 --board=esp32dev
+          pio lib --global uninstall TinyGSM