Pin GitHub Actions to commit SHAs (#46)

Signed-off-by: Divya Madala <divyaasm@amazon.com>

Author: Divyaasm

.github/workflows/backport.yml

@@ -26,15 +26,15 @@ jobs:
     steps:
       - name: GitHub App token
         id: github_app_token
-        uses: tibdex/github-app-token@v1.5.0
+        uses: tibdex/github-app-token@1901dc7d52169e70c27a8da37aef0d423e2867a2 # v1.5.0
         with:
           app_id: ${{ secrets.APP_ID }}
           private_key: ${{ secrets.APP_PRIVATE_KEY }}
           # opensearch-trigger-bot installation ID
           installation_id: 22958780
 
       - name: Backport
-        uses: VachaShah/backport@v2.2.0
+        uses: VachaShah/backport@142d3b8a8c70dc54db515e653e5ed3c3fac64100 # v2.2.0
         with:
           github_token: ${{ steps.github_app_token.outputs.token }}
           head_template: backport/backport-<%= number %>-to-<%= base %>

.github/workflows/dco.yml

@@ -9,10 +9,10 @@ jobs:
     steps:
     - name: Get PR Commits
       id: 'get-pr-commits'
-      uses: tim-actions/get-pr-commits@v1.1.0
+      uses: tim-actions/get-pr-commits@55b867b9b28954e6f5c1a0fe2f729dc926c306d0 # v1.1.0
       with:
         token: ${{ secrets.GITHUB_TOKEN }}
     - name: DCO Check
-      uses: tim-actions/dco@v1.1.0
+      uses: tim-actions/dco@f2279e6e62d5a7d9115b0cb8e837b777b1b02e21 # v1.1.0
       with:
         commits: ${{ steps.get-pr-commits.outputs.commits }}

.github/workflows/delete_backport_branch.yml

@@ -10,6 +10,6 @@ jobs:
     if: startsWith(github.event.pull_request.head.ref,'backport/')
     steps:
       - name: Delete merged branch
-        uses: SvanBoxel/delete-merged-branch@main
+        uses: SvanBoxel/delete-merged-branch@2b5b058e3db41a3328fd9a6a58fd4c2545a14353 # main
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}