Fix path to repository-wide exclude file (#1837)

## Changes

This file is at `info/exclude`, and not `info/excludes`.

Also see https://git-scm.com/docs/gitignore.

## Tests

Manually confirmed that these ignore patterns are now picked up. I
created a repository with a pattern in this file and ran `sync` to
confirm it ignores files matching the pattern.

libs/git/repository.go

@@ -252,8 +252,8 @@ func NewRepository(path vfs.Path) (*Repository, error) {
 		newStringIgnoreRules([]string{
 			".git",
 		}),
-		// Load repository-wide excludes file.
-		repo.newIgnoreFile(".git/info/excludes"),
+		// Load repository-wide exclude file.
+		repo.newIgnoreFile(".git/info/exclude"),
 		// Load root gitignore file.
 		repo.newIgnoreFile(".gitignore"),
 	}