Upgrade to Laravel 12

- laravel/framework ^11.45 -> ^12.0 (installed 12.63.0)
- phpunit/phpunit ^10.5 -> ^11.0; migrate phpunit.xml to the 11.5 schema
- graham-campbell/github ^12.5 -> ^13.0 (v12 caps illuminate/support at ^11)
- Carbon 3 pulled in by L12; no application code changes required
- gitignore /.phpunit.cache

Full suite green: 59 tests, 128 assertions (1 skipped).

phpunit.xml

@@ -1,10 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd" bootstrap="vendor/autoload.php" colors="true">
-  <coverage processUncoveredFiles="true">
-    <include>
-      <directory suffix=".php">./app</directory>
-    </include>
-  </coverage>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/11.5/phpunit.xsd" bootstrap="vendor/autoload.php" colors="true" cacheDirectory=".phpunit.cache">
   <testsuites>
     <testsuite name="Unit">
       <directory suffix="Test.php">./tests/Unit</directory>
@@ -21,8 +16,13 @@
     <!-- <env name="DB_DATABASE" value=":memory:"/> -->
     <env name="MAIL_MAILER" value="array"/>
     <env name="PULSE_ENABLED" value="false"/>
-        <env name="QUEUE_CONNECTION" value="sync"/>
+    <env name="QUEUE_CONNECTION" value="sync"/>
     <env name="SESSION_DRIVER" value="array"/>
     <env name="TELESCOPE_ENABLED" value="false"/>
   </php>
+  <source>
+    <include>
+      <directory suffix=".php">./app</directory>
+    </include>
+  </source>
 </phpunit>