ci: pin pnpm version in release workflow

Avoids the buggy pnpm self-switch (bootstrap 11.7.0 -> packageManager
version) that crashes with 'Cannot use in operator to search for
integrity in undefined' during the Install pnpm step.

Author: posva

.github/workflows/release.yml

@@ -122,6 +122,10 @@ jobs:
 
       - name: Install pnpm
         uses: pnpm/action-setup@0ebf47130e4866e96fce0953f49152a61190b271 # v6.0.9
+        with:
+          # pin to avoid the buggy self-switch (11.7.0 → packageManager version)
+          # that crashes with "Cannot use 'in' operator to search for 'integrity'"
+          version: 11.12.0
 
       - name: Setup node
         uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0