Change checkbox to handle lowercase

GitHubIssueFormsParser/src/GitHubIssuesParserCli/IssueFormBodies/IssueFormItems/Checkboxes/IssueFormCheckBoxesText.cs

@@ -25,6 +25,13 @@ private static List<IssueFormCheckboxOption> CreateCheckboxOptions(string option
                         .TrimIssueText();
                     isChecked = true;
                 }
+                else if (optionText.StartsWith("- [x]", StringComparison.Ordinal))
+                {
+                    label = optionText
+                        .TrimStart([.. "- [x]"])
+                        .TrimIssueText();
+                    isChecked = true;
+                }
                 else if (optionText.StartsWith("- [ ]", StringComparison.Ordinal))
                 {
                     label = optionText

GitHubIssueFormsParser/tests/GitHubIssuesParserCli.Tests/CliIntegration/CliIntegrationTests.cs

@@ -117,6 +117,8 @@ public async Task TemplateFilepathOptionValidation2()
 
     /// <summary>
     /// Tests the correct value for the options that can be used with the 'parse-issue-form' command.
+    /// This test uses an issue body where the checkboxes use both an Uppercase and Lowercase 'X' or aren't
+    /// checked.
     /// </summary>
     [Theory]
     [InlineData("-i", "-t")]

GitHubIssueFormsParser/tests/GitHubIssuesParserCli.Tests/TestFiles/IssueBody.md

@@ -29,6 +29,6 @@ Another line:
 ### Which operating systems have you used?
 
 - [X] macOS
-- [X] Windows
+- [x] Windows
 - [ ] Linux
 - [ ] I don't know