Change: Convert ReleaseType and OutoutFormat into StrEnum's

With this change they can be used more easily. Especially for argument
parsing.

pontos/release/helper.py

@@ -3,9 +3,9 @@
 # SPDX-License-Identifier: GPL-3.0-or-later
 #
 
-from enum import Enum
 from typing import Optional
 
+from pontos.enum import StrEnum
 from pontos.git import Git, GitError
 from pontos.terminal import Terminal
 from pontos.version import Version, VersionCalculator, VersionError
@@ -14,7 +14,7 @@
 DEFAULT_CHUNK_SIZE = 4096
 
 
-class ReleaseType(Enum):
+class ReleaseType(StrEnum):
     """
     Type of the release. Used to determine the next release version.
 

pontos/release/show.py

@@ -4,9 +4,10 @@
 
 import json
 from argparse import Namespace
-from enum import Enum, IntEnum, auto
+from enum import IntEnum, auto
 from typing import Optional
 
+from pontos.enum import StrEnum
 from pontos.errors import PontosError
 from pontos.git import Git
 from pontos.github.actions import ActionIO
@@ -29,7 +30,7 @@ class ShowReleaseReturnValue(IntEnum):
     NO_RELEASE_VERSION = auto()
 
 
-class OutputFormat(Enum):
+class OutputFormat(StrEnum):
     ENV = "env"
     JSON = "json"
     GITHUB_ACTION = "github-action"