fix: normalize gitDir path for Windows compatibility

Author: Iiro Jäppinen

src/resolveGitDir.js

@@ -1,12 +1,13 @@
 'use strict'
 
 const execGit = require('./execGit')
+const path = require('path')
 const printErrors = require('./printErrors')
 
 module.exports = async function resolveGitDir() {
   try {
     const gitDir = await execGit(['rev-parse', '--show-toplevel'])
-    return gitDir
+    return path.normalize(gitDir)
   } catch (error) {
     printErrors(error)
     return null