Pre-commit: replace old format string interpolation with f-strings

Since Python 3.5 is no longer supported, format string interpolations
can now be replaced by f-strings, introduced in Python 3.6, which are
more readable, require less characters and are more efficient.

All of the conversions were done automatically with the linting tool
`flynt` which is also added as a pre-commit hook. It is added before the
`yapf` step because since `flynt` will touch formatting, `yapf` will
then get a chance to check it.

.pre-commit-config.yaml

@@ -8,6 +8,15 @@ repos:
     -   id: mixed-line-ending
     -   id: trailing-whitespace
 
+-   repo: https://github.com/ikamensh/flynt/
+    rev: '0.55'
+    hooks:
+    -   id: flynt
+        args: [
+            '--line-length=120',
+            '--fail-on-change',
+        ]
+
 -   repo: https://github.com/pre-commit/mirrors-yapf
     rev: v0.30.0
     hooks:

aiida_pseudo/cli/install.py

@@ -102,7 +102,7 @@ def cmd_install_sssp(version, functional, protocol, traceback):
         url_archive = f'{URL_SSSP_BASE}/SSSP_{version}_{functional}_{protocol}.tar.gz'
         filepath_archive = os.path.join(dirpath, 'archive.tar.gz')
 
-        url_metadata = '{}/SSSP_{}_{}_{}.json'.format(URL_SSSP_BASE, version, functional, protocol)
+        url_metadata = f'{URL_SSSP_BASE}/SSSP_{version}_{functional}_{protocol}.json'
         filepath_metadata = os.path.join(dirpath, 'metadata.json')
 
         with attempt('downloading selected pseudo potentials archive... ', include_traceback=traceback):
@@ -121,7 +121,7 @@ def cmd_install_sssp(version, functional, protocol, traceback):
                 handle.flush()
                 handle.seek(0)
                 metadata = json.load(handle)
-                description += '\nPseudo metadata md5: {}'.format(md5_file(filepath_metadata))
+                description += f'\nPseudo metadata md5: {md5_file(filepath_metadata)}'
 
         with attempt('unpacking archive and parsing pseudos... ', include_traceback=traceback):
             family = create_family_from_archive(SsspFamily, label, filepath_archive)

aiida_pseudo/cli/utils.py

@@ -25,7 +25,7 @@ def attempt(message, exception_types=Exception, include_traceback=False):
         echo.echo_highlight(' [FAILED]', color='error', bold=True)
         message = str(exception)
         if include_traceback:
-            message += '\n' + ''.join(traceback.format_exception(*sys.exc_info()))
+            message += f"\n{''.join(traceback.format_exception(*sys.exc_info()))}"
         echo.echo_critical(message)
     else:
         echo.echo_highlight(' [OK]', color='success', bold=True)