Pin actions to a full length commit SHA (#2765)

- Pinned actions by SHA https://github.com/ossf/scorecard/blob/main/docs/checks.md#pinned-dependencies
- Included permissions for the action. https://github.com/ossf/scorecard/blob/main/docs/checks.md#token-permissions

>Pin actions to a full length commit SHA

>Pinning an action to a full length commit SHA is currently the only way to use an action as an immutable release. Pinning to a particular SHA helps mitigate the risk of a bad actor adding a backdoor to the action's repository, as they would need to generate a SHA-1 collision for a valid Git object payload.

https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions

Also, dependabot supports upgrade based on SHA.

Signed-off-by: naveensrinivasan <172697+naveensrinivasan@users.noreply.github.com>s

.github/workflows/linux.yml

@@ -8,6 +8,9 @@ on:
     branches: [ master ]
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -15,17 +18,17 @@ jobs:
       matrix:
         go: [1.14, 1.16]
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@629c2de402a417ea7690ca6ce3f33229e27606a5 # v2
       with:
         fetch-depth: 0
 
     - name: Set up Go
-      uses: actions/setup-go@v2
+      uses: actions/setup-go@bfdd3570ce990073878bf10f6b2d79082de49492 # v2
       with:
         go-version: ${{ matrix.go }}
 
     - name: Setup Ruby
-      uses: ruby/setup-ruby@v1.62.0
+      uses: ruby/setup-ruby@5aaa89ff0d7bb9c02d18c0008a98d24f38acbbbb # v1.62.0
       with:
         ruby-version: 3.0.0