feat: Added Swift language support (#335)

Hello,

Thanks for sharing this awesome project.
This little patch fixes the following issue with Gitlab integration:

1. I have added .swift files to the languageMap to enable Swift code reviews.

packages/code-review-gpt/src/review/constants.ts

@@ -55,6 +55,7 @@ export const languageMap: { [key: string]: string } = {
   ".vue": "Vue",
   ".tf": "Terraform",
   ".hcl": "Terraform",
+  ".swift":"Swift"
 };
 
 export const supportedFiles = new Set(Object.keys(languageMap));