Write directly to file objects when possible.

Instead of decoding the stdout of subprocess.run and then doing our own
writes, just hand subprocess the file object and let it write directly.

src/aurman/classes.py

@@ -1002,15 +1002,8 @@ def show_pkgbuild(self, noedit: bool = False, show_changes: bool = False,
 
         # if last commit seen hash file does not exist - create
         if not os.path.isfile(last_commit_hash_file):
-            empty_tree_hash = run(
-                ["git", "hash-object", "-t", "tree", "/dev/null"],
-                stdout=PIPE,
-                stderr=DEVNULL,
-                universal_newlines=True
-            ).stdout.strip()
-
             with open(last_commit_hash_file, 'w') as f:
-                f.write(empty_tree_hash)
+                run(["git", "hash-object", "-t", "tree", "/dev/null"], stdout=f, stderr=DEVNULL)
 
         current_commit_hash = run(
             ["git", "rev-parse", "HEAD"], stdout=PIPE, stderr=DEVNULL, cwd=package_dir, universal_newlines=True