ci: use cache in github actions (#164)

* ci: use cache in github actions

* address review comments

Author: thijstriemstra

integration/ci/github-actions.rst

@@ -58,13 +58,25 @@ This variant is default choice for native PlatformIO projects:
         runs-on: ubuntu-latest
 
         steps:
-        - uses: actions/checkout@v1
+        - uses: actions/checkout@v2
+        - name: Cache pip
+          uses: actions/cache@v2
+          with:
+            path: ~/.cache/pip
+            key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
+            restore-keys: |
+              ${{ runner.os }}-pip-
+        - name: Cache PlatformIO
+          uses: actions/cache@v2
+          with:
+            path: ~/.platformio
+            key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
         - name: Set up Python
-          uses: actions/setup-python@v1
-        - name: Install dependencies
+          uses: actions/setup-python@v2
+        - name: Install PlatformIO
           run: |
             python -m pip install --upgrade pip
-            pip install platformio
+            pip install --upgrade platformio
         - name: Run PlatformIO
           run: pio run -e <ID_1> -e <ID_2> -e <ID_N>
 
@@ -91,13 +103,24 @@ and boards from command line interface:
             example: [path/to/test/file.c, examples/file.ino, path/to/test/directory]
 
         steps:
-        - uses: actions/checkout@v1
+        - uses: actions/checkout@v2
+        - name: Cache pip
+          uses: actions/cache@v2
+          with:
+            path: ~/.cache/pip
+            key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
+            restore-keys: ${{ runner.os }}-pip-
+        - name: Cache PlatformIO
+          uses: actions/cache@v2
+          with:
+            path: ~/.platformio
+            key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
         - name: Set up Python
-          uses: actions/setup-python@v1
-        - name: Install dependencies
+          uses: actions/setup-python@v2
+        - name: Install PlatformIO
           run: |
             python -m pip install --upgrade pip
-            pip install platformio
+            pip install --upgrade platformio
         - name: Run PlatformIO
           run: pio ci --board=<ID_1> --board=<ID_2> --board=<ID_N>
           env:
@@ -169,14 +192,27 @@ Integration for USB_Host_Shield_2.0 project. The ``workflow.yml`` configuration
             example: [examples/Bluetooth/PS3SPP/PS3SPP.ino, examples/pl2303/pl2303_gps/pl2303_gps.ino]
 
         steps:
-        - uses: actions/checkout@v1
+        - uses: actions/checkout@v2
+        - name: Cache pip
+          uses: actions/cache@v2
+          with:
+            path: ~/.cache/pip
+            key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
+            restore-keys: |
+              ${{ runner.os }}-pip-
+        - name: Cache PlatformIO
+          uses: actions/cache@v2
+          with:
+            path: ~/.platformio
+            key: ${{ runner.os }}-${{ hashFiles('**/lockfiles') }}
+
         - name: Set up Python
-          uses: actions/setup-python@v1
+          uses: actions/setup-python@v2
 
-        - name: Install dependencies
+        - name: Install PlatformIO
           run: |
             python -m pip install --upgrade pip
-            pip install platformio
+            pip install --upgrade platformio
             wget https://github.com/xxxajk/spi4teensy3/archive/master.zip -O /tmp/spi4teensy3.zip
             unzip /tmp/spi4teensy3.zip -d /tmp