[Release|CI/CD] Bump Zepter version in post crates action (#10885)

Resolving following error lines:

https://github.com/paritytech/polkadot-sdk/actions/runs/21254581447/job/61165383938#step:17:15

---------

Co-authored-by: Egor_P <[email protected]>

Author: BDevParity

.github/workflows/release-60_post-crates-release-activities.yml

@@ -200,6 +200,10 @@ jobs:
           # Show git diff to see what changed
           git diff --stat
 
+      - name: Install newer Zepter
+        run: |
+          cargo install [email protected] --locked -q && zepter --version
+
       - name: Run Zepter - check issues
         run: |
           echo "Running zepter run check to identify issues..."
@@ -296,9 +300,6 @@ jobs:
             BASE_RELEASE="$FULL_RELEASE"
           fi
 
-          BASE_RELEASE_UPPER=$(echo "$BASE_RELEASE" | tr '[:lower:]' '[:upper:]')
-          echo "Base release branch (upper): $BASE_RELEASE_UPPER"
-
           # Check if PR already exists
           EXISTING_PR=$(gh pr list --head "$BRANCH_NAME" --base "$BASE_RELEASE" --json number --jq '.[0].number')
 
@@ -308,7 +309,7 @@ jobs:
           else
             echo "Creating PR from $BRANCH_NAME to $BASE_RELEASE..."
             gh pr create \
-              --title "[${BASE_RELEASE_UPPER}] Post crates release activities for $FULL_RELEASE" \
+              --title "[${BASE_RELEASE}] Post crates release activities for $FULL_RELEASE" \
               --body "Automated PR containing post-crates-release activities:
           - NODE_VERSION bumps (if selected)
           - Path dependencies replacement