ci: update_traces_checksum: fix E501 line too long

Currently the update_traces_checksum script prints a label verification
request with a line that is 167 characters long.

Split the long line to make it more readable. Update the flake8
configuration to enforce a maximum line length of 159 characters to ensure
consistency.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32602>

.gitlab-ci/.flake8

@@ -2,7 +2,7 @@
 exclude = .venv*,
 
 # PEP 8 Style Guide limits line length to 79 characters
-max-line-length = 167
+max-line-length = 159
 
 ignore =
     # continuation line under-indented for hanging indent

bin/ci/update_traces_checksum.py

@@ -96,7 +96,11 @@ def gather_results(
                         continue
 
                     if "label" in target['traces'][trace][dev_name]:
-                        print(f'{dev_name}: {trace}: please verify that label {Fore.BLUE}{target["traces"][trace][dev_name]["label"]}{Style.RESET_ALL} is still valid')
+                        print(
+                            f"{dev_name}: {trace}: please verify that label "
+                            f"{Fore.BLUE}{target['traces'][trace][dev_name]['label']}{Style.RESET_ALL} "
+                            "is still valid"
+                             )
 
                     print(Fore.GREEN + f'{dev_name}: {trace}: checksum updated' + Style.RESET_ALL)
                     target['traces'][trace][dev_name]['checksum'] = checksum