refactor(git): change default branch name to main

  ## what
  - change default branch name to `main`

  ## how

  ## why

  ## where
  - ./tools/git/.gitconfig

  ## usage

  ## issue or pull request

tools/git/.gitconfig

@@ -91,6 +91,6 @@
 [gpg "ssh"]
   allowedSignersFile = /Users/umar/.ssh/allowed_signers
 [init]
-	defaultBranch = master
+	defaultBranch = main
 [diff "exif"]
 	textconv = exiftool