refactor: move constants to git_flow module

src/git_flow/git.py

@@ -1,13 +1,8 @@
 import subprocess
 
+from git_flow import FLOWCONFIG_FILENAME
 from git_flow.io import *
 
-FLOWCONFIG_FILE = ".flowconfig"
-
-CHANGELOG_FILE = "CHANGELOG.md"
-
-BUMP_VERSION = "chore: bump version and update CHANGELOG.md [skip ci]"
-
 
 class Git:
     class Status:
@@ -42,7 +37,7 @@ class Git:
 
     @staticmethod
     def flow_config(*args, **kwargs):
-        return Git("config", *args, file=FLOWCONFIG_FILE, **kwargs)
+        return Git("config", *args, file=FLOWCONFIG_FILENAME, **kwargs)
 
     @staticmethod
     def get_current_branch():