fix: remove redundant composer require steps in code-quality workflow

szepeviktor/phpstan-wordpress, wp-coding-standards/wpcs, and
dealerdirect/phpcodesniffer-composer-installer are already declared in
composer.json require-dev. The extra 'composer require' steps after
'composer install' caused a second packagist.org network hit that timed
out in CI, failing the PHPStan Static Analysis job.

Fixes the Code Quality CI failure on PR #51 (issue #45).

.github/workflows/code-quality.yml

@@ -29,11 +29,6 @@ jobs:
       - name: Install dependencies
         run: composer install --prefer-dist --no-progress
 
-      - name: Install WordPress Coding Standards
-        run: |
-          composer require --dev wp-coding-standards/wpcs dealerdirect/phpcodesniffer-composer-installer
-          vendor/bin/phpcs --config-set installed_paths vendor/wp-coding-standards/wpcs
-
       - name: Run PHPCS
         run: composer phpcs
         continue-on-error: true
@@ -61,9 +56,6 @@ jobs:
       - name: Install dependencies
         run: composer install --prefer-dist --no-progress
 
-      - name: Install PHPStan WordPress stubs
-        run: composer require --dev szepeviktor/phpstan-wordpress
-
       - name: Run PHPStan
         run: composer phpstan
         continue-on-error: true