Fix quotation

Fixes:
=> ERROR [stage-0 22/23] RUN "/app"/bin/docker_entrypoint.sh version 2>&1 | tee -a /VERSION.txt                                       1.7s 
------                                                                                                                                      
 > [stage-0 22/23] RUN "/app"/bin/docker_entrypoint.sh version 2>&1 | tee -a /VERSION.txt:                                                  
1.665 Traceback (most recent call last):                                                                                                    
1.665   File "/usr/local/bin/archivebox", line 5, in <module>                                                                               
1.665     from archivebox.cli import main                                                                                                   
1.665   File "/app/archivebox/cli/__init__.py", line 83, in <module>
1.665     SUBCOMMANDS = list_subcommands()
1.665                   ^^^^^^^^^^^^^^^^^^
1.665   File "/app/archivebox/cli/__init__.py", line 43, in list_subcommands
1.665     module = import_module('.archivebox_{}'.format(subcommand), __package__)
1.665              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1.665   File "/usr/local/lib/python3.11/importlib/__init__.py", line 126, in import_module
1.665     return _bootstrap._gcd_import(name[level:], package, level)
1.665            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1.666   File "/app/archivebox/cli/archivebox_add.py", line 11, in <module>
1.666     from ..main import add
1.666   File "/app/archivebox/main.py", line 233
1.666     f'COMMIT_HASH={COMMIT_HASH[:7] if COMMIT_HASH else 'unknown'}',
1.666                                                         ^^^^^^^
1.666 SyntaxError: f-string: expecting '}'

archivebox/main.py

@@ -230,7 +230,7 @@ def version(quiet: bool=False,
         p = platform.uname()
         print(
             'ArchiveBox v{}'.format(get_version(CONFIG)),
-            f'COMMIT_HASH={COMMIT_HASH[:7] if COMMIT_HASH else 'unknown'}',
+            f'COMMIT_HASH={COMMIT_HASH[:7] if COMMIT_HASH else "unknown"}',
             f'BUILD_TIME={BUILD_TIME}',
         )
         print(