Use case insensitive comparison for config filenames

Author: Bi0T1N

src/GitVersion.Configuration.Tests/Configuration/ConfigurationFileLocatorTests.cs

@@ -73,6 +73,18 @@ public void NoWarnOnGitVersionYmlFile(string configurationFile)
             Should.NotThrow(() => this.configurationProvider.ProvideForDirectory(this.repoPath));
         }
 
+        [TestCase(ConfigurationFileLocator.DefaultFileName)]
+        [TestCase(ConfigurationFileLocator.DefaultAlternativeFileName)]
+        [TestCase(ConfigurationFileLocator.DefaultFileNameDotted)]
+        [TestCase(ConfigurationFileLocator.DefaultAlternativeFileNameDotted)]
+        public void NoWarnOnLowercasedGitVersionYmlFile(string configurationFile)
+        {
+            var lowercasedConfigurationFile = configurationFile.ToLower();
+            using var _ = this.fileSystem.SetupConfigFile(path: this.repoPath, fileName: lowercasedConfigurationFile);
+
+            Should.NotThrow(() => this.configurationProvider.ProvideForDirectory(this.repoPath));
+        }
+
         [Test]
         public void NoWarnOnNoGitVersionYmlFile() => Should.NotThrow(() => this.configurationProvider.ProvideForDirectory(this.repoPath));
     }

src/GitVersion.Configuration/ConfigurationFileLocator.cs

@@ -74,7 +74,7 @@ private void WarnAboutAmbiguousConfigFileSelection(string? workingDirectory, str
 
         if (!hasConfigInProjectRootDirectory && !hasConfigInWorkingDirectory)
         {
-            if (!SupportedConfigFileNames.Any(entry => entry.Equals(this.ConfigurationFile)))
+            if (!SupportedConfigFileNames.Any(entry => entry.Equals(this.ConfigurationFile, StringComparison.OrdinalIgnoreCase)))
             {
                 workingConfigFile = PathHelper.Combine(workingDirectory, this.ConfigurationFile);
                 projectRootConfigFile = PathHelper.Combine(projectRootDirectory, this.ConfigurationFile);