fix: replace pnpm to npm install (#436)

## Description

> Describe what you did and why.

**Related issue (if any):** fixes #issue_number_goes_here

## Checklist

- [x] I have followed this repository's contributing guidelines.
- [x] I will adhere to the project's code of conduct.

## Additional information

> Anything else?

## Summary by Sourcery

CI:
- Switch the release GitHub Actions workflow from using pnpm to npm to
install pnpm globally.

Author: a-oren

.github/workflows/release.yml

@@ -92,7 +92,7 @@ jobs:
           echo "Will publish to Maven Central: ${{ steps.check_maven.outputs.maven_exists == 'false' }}"
 
       - name: Install pnpm
-        run: pnpm install -g pnpm
+        run: npm install -g pnpm
 
       - name: Compute Maven profiles
         id: compute_profiles