fix: Use semver -alpha1 style versioning for python

Author: tux3

tbump.toml

@@ -8,13 +8,11 @@ regex = '''
   (?P<minor>\d+)
   \.
   (?P<patch>\d+)
-  (
-     (
-     a(?P<alpha>\d+)
-     |
-     b(?P<beta>\d+)
-     )
-  )?
+    (
+      -
+      (?P<lifecycle>alpha|beta)
+      (?P<release>\d+)
+    )?
   )
   '''