python: Fix multiline quotes in a single line

An example case,
```python
mem_side_port = RequestPort(
    "This port sends requests and " "receives responses"
)
```

This is the residue of running the python formatter.
This is done by finding all tokens matching the regex `"\s"(?![.;"])`
and manually replacing them by empty strings.

Change-Id: Icf223bbe889e5fa5749a81ef77aa6e721f38b549
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/66111
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

util/maint/list_changes.py

@@ -179,14 +179,14 @@ def _main():
         "-u",
         type=str,
         default="origin/master",
-        help="Upstream branch for comparison. " "Default: %(default)s",
+        help="Upstream branch for comparison. Default: %(default)s",
     )
     parser.add_argument(
         "--feature",
         "-f",
         type=str,
         default="HEAD",
-        help="Feature branch for comparison. " "Default: %(default)s",
+        help="Feature branch for comparison. Default: %(default)s",
     )
     parser.add_argument(
         "--show-unknown",
@@ -199,7 +199,7 @@ def _main():
     parser.add_argument(
         "--deep-search",
         action="store_true",
-        help="Use a deep search to find incorrectly " "rebased changes",
+        help="Use a deep search to find incorrectly rebased changes",
     )
     parser.add_argument(
         "paths",