fix(ci): update snapshots after CDK version sync in release workflow (#1033)

The release workflow syncs @aws/agentcore-cdk to the latest npm version
in the asset template, but never updates the snapshot file. This causes
the asset snapshot test to fail because the snapshot still holds the old
version string.

Author: aidandaly24

.github/workflows/release-main-and-preview.yml

@@ -120,6 +120,7 @@ jobs:
                 fs.writeFileSync('$TEMPLATE_PKG', JSON.stringify(pkg, null, 2) + '\n');
               "
               echo "✅ Updated @aws/agentcore-cdk: $CURRENT_CDK -> $LATEST_CDK"
+              npm run test:update-snapshots
             fi
           fi
 
@@ -218,6 +219,7 @@ jobs:
                 fs.writeFileSync('$TEMPLATE_PKG', JSON.stringify(pkg, null, 2) + '\n');
               "
               echo "✅ Updated @aws/agentcore-cdk: $CURRENT_CDK -> $LATEST_CDK"
+              npm run test:update-snapshots
             fi
           fi