Bump shivammathur/setup-php from 2.20.1 to 2.21.0

Bumps [shivammathur/setup-php](https://github.com/shivammathur/setup-php) from 2.20.1 to 2.21.0.
- [Release notes](https://github.com/shivammathur/setup-php/releases)
- [Commits](shivammathur/setup-php@2.20.1...2.21.0)

---
updated-dependencies:
- dependency-name: shivammathur/setup-php
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/php-ci.yml

@@ -23,7 +23,7 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Use PHP ${{ matrix.php_version }}
-        uses: shivammathur/setup-php@2.20.1
+        uses: shivammathur/setup-php@2.21.0
         with:
           php-version: ${{ matrix.php_version }}
 #          extension-csv: xdebug, mbstring, curl, zip, dom, simplexml, intl, mysql