PLT-621 chore(ci/actions): pin GitHub Actions SHAs (#34)

Author: buschtoens

.github/workflows/CI.yml

@@ -30,9 +30,9 @@ jobs:
           - --no-lockfile
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v2
+        uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2
       - name: Install Node.js
-        uses: actions/setup-node@v2
+        uses: actions/setup-node@7c12f8017d5436eb855f1ed4399f037a36fbd9e8 # v2
         with:
           node-version: ${{ matrix.node }}
       - name: Install Dependencies