fix: pin up/download action

Author: SMillerDev

.github/workflows/ci.yml

@@ -102,7 +102,7 @@ jobs:
                     -out=tfplan
 
       - name: Upload Plan Artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: tfplan
           path: tfplan
@@ -137,7 +137,7 @@ jobs:
         run: tofu init
 
       - name: Download Plan Artifact
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e # v4.2.1
         with:
           name: tfplan