Update SolverTest.php

tests/Composer/Test/DependencyResolver/SolverTest.php

@@ -709,7 +709,7 @@ class SolverTest extends TestCase
             $msg .= "Potential causes:\n";
             $msg .= " - A typo in the package name\n";
             $msg .= " - The package is not available in a stable-enough version according to your minimum-stability setting\n";
-            $msg .= "   see <https://groups.google.com/d/topic/composer-dev/_g3ASeIFlrc/discussion> for more details.\n\n";
+            $msg .= "   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.\n\n";
             $msg .= "Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.";
             $this->assertEquals($msg, $e->getMessage());
         }