♻️ refactor(pep723): verbose regex and covdefaults pragmas

Author: gaborbernat

src/tox/tox_env/python/virtual_env/pep723.py

@@ -5,15 +5,25 @@
 import re
 import sys
 from dataclasses import dataclass, field
+from typing import Final
 
-if sys.version_info >= (3, 11):
+if sys.version_info >= (3, 11):  # pragma: >=3.11 cover
     import tomllib
-else:
+else:  # pragma: <3.11 cover
     import tomli as tomllib
 
 
-SCRIPT_METADATA_RE = re.compile(
-    r"(?m)^# /// (?P<type>[a-zA-Z0-9-]+)$\s(?P<content>(^#(| .*)$\s)+)^# ///$",
+SCRIPT_METADATA_RE: Final = re.compile(
+    r"""
+    (?m)
+    ^[#][ ]///[ ](?P<type>[a-zA-Z0-9-]+)$  # opening: # /// <type>
+    \s                                      # blank line or whitespace
+    (?P<content>                            # TOML content lines:
+        (?:^[#](?:| .*)$\s)+               #   each line starts with # (optionally followed by space + text)
+    )
+    ^[#][ ]///$                             # closing: # ///
+    """,
+    re.VERBOSE,
 )