fix(git.ts): add relative flag to git diff command (di-sukharev#37)

The relative flag has been added to the git diff command in the
getStagedFiles function. This flag makes the output of the command
relative to the current working directory, which makes it easier to work
with the file paths and enables executing opencommit from anywhere in
the repository, not just from the root.

Author: Moret84

src/utils/git.ts

@@ -29,7 +29,8 @@ export const getStagedFiles = async (): Promise<string[]> => {
   const { stdout: files } = await execa('git', [
     'diff',
     '--name-only',
-    '--cached'
+    '--cached',
+    '--relative'
   ]);
 
   if (!files) return [];