Pin actions to a full length commit SHA

- 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 upgrading based on SHA.

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

.github/workflows/main.yml

@@ -9,6 +9,9 @@ env:
   GOPROXY: https://proxy.golang.org
   GOPATH: ${{ github.workspace }}/go
 
+permissions:
+  contents: read
+
 jobs:
   build-linux-amd64:
     runs-on: ubuntu-20.04