Fixed extra capture group in PEP440 parser

Author: coordt

tests/fixtures/pep440.toml

@@ -10,15 +10,13 @@ tag_message = "Bump version: {current_version} → {new_version}"
 current_version = "1.0.0"
 parse = """(?x)
 (?:
-    (?P<release>
-        (?P<major>[0-9]+)
+    (?P<major>[0-9]+)
+    (?:
+        \\.(?P<minor>[0-9]+)
         (?:
-            \\.(?P<minor>[0-9]+)
-            (?:
-                \\.(?P<patch>[0-9]+)
-            )?
+            \\.(?P<patch>[0-9]+)
         )?
-    )
+    )?
     (?P<prerelease>
         [-_\\.]?
         (?P<pre_label>a|b|rc)