Update actions/checkout action to v2.7.0

Change-Id: I79ce450d5da5a01fe9847603866b576a8e18e2be
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 3d9d22b..495897b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -10,7 +10,7 @@
     runs-on: ubuntu-latest
     steps:
       - name: Checkout master
-        uses: actions/checkout@ec3a7ce113134d7a93b817d10a8272cb61118579 #2.4.0
+        uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2.7.0
         with:
           fetch-depth: 0