Handle closing files after reading for hashing (#199)

Makefile

@@ -27,3 +27,7 @@ lint:
 	sorti --check .
 	black --check .
 	mypy .
+
+format:
+	sorti .
+	black .

collectfast/strategies/base.py

@@ -89,7 +89,13 @@ def get_gzipped_local_file_hash(
     @lru_cache(maxsize=None)
     def get_local_file_hash(self, path: str, local_storage: Storage) -> str:
         """Create md5 hash from file contents."""
-        contents = local_storage.open(path).read()
+        # Read file contents and handle file closing
+        file = local_storage.open(path)
+        try:
+            contents = file.read()
+        finally:
+            file.close()
+
         file_hash = hashlib.md5(contents).hexdigest()
 
         # Check if content should be gzipped and hash gzipped content