ci: use upstream patch

To get the XDebug 3 INI setting we need, we require a bug fix branch
from upstream. Switch to that for now.

@see shivammathur/setup-php#392

.github/workflows/ci-2.x.yml

@@ -45,8 +45,9 @@ jobs:
         # has paths for with- and without- XDebug, and we want to test both of them.
         # However, we require XDebug for code coverage, so before XDebug 3 there was
         # no way to test the without-XDebug code path. Now we can, so we do.
+        # Note: INI values with embedded commas need to have their value quoted.
         # @see https://xdebug.org/docs/all_settings#mode
-        xdebug3-mode: ["xdebug.mode=develop,coverage", "xdebug.mode=coverage"]
+        xdebug3-mode: ["xdebug.mode='develop,coverage'", "xdebug.mode=coverage"]
         include:
           # 7.4 introduced an engine wide flag that disables arguments in
           # backtraces. The default in 7.4 is On. However, we have tests that
@@ -78,11 +79,11 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Install PHP and composer environment
-        uses: shivammathur/setup-php@v2
+        uses: shivammathur/setup-php@develop
         with:
           php-version: ${{ matrix.php }}
           extensions: curl
-          ini-values: ${{ matrix.ini }}, "${{ matrix.xdebug3-mode }}"
+          ini-values: ${{ matrix.ini }}, ${{ matrix.xdebug3-mode }}
           coverage: xdebug
 
       - name: Get composer cache directory