Fix docs build (#5492)

Seems like readthedocs build expects docs dependencies to be available
as an extra, see one of the failing builds:
https://app.readthedocs.org/projects/beets/builds/26079213/.

You can see this has been failing due to missing 'pydata_sphinx_theme'
which is one of our dependencies:

```
    raise ThemeError(__('no theme named %r found (missing theme.toml?)') % name)
    sphinx.errors.ThemeError: no theme named 'pydata_sphinx_theme' found (missing theme.toml?)
    Theme error:
    no theme named 'pydata_sphinx_theme' found (missing theme.toml?)
```

.github/workflows/ci.yaml

@@ -1,6 +1,6 @@
 name: Test
 on:
-  pull_request_target:
+  pull_request:
   push:
     branches:
       - master

.github/workflows/lint.yml

@@ -1,7 +1,7 @@
 name: Lint check
 run-name: Lint code
 on:
-  pull_request_target:
+  pull_request:
   push:
     branches:
       - master
@@ -125,7 +125,7 @@ jobs:
           cache: poetry
 
       - name: Install dependencies
-        run: poetry install --only=docs
+        run: poetry install --extras=docs
 
       - name: Add Sphinx problem matcher
         run: echo "::add-matcher::.github/sphinx-problem-matcher.json"

beetsplug/convert.py

@@ -84,6 +84,7 @@ def get_format(fmt=None):
 
     return (command.encode("utf-8"), extension.encode("utf-8"))
 
+
 def in_no_convert(item: Item) -> bool:
     no_convert_query = config["convert"]["no_convert"].as_str()
 
@@ -92,7 +93,8 @@ def in_no_convert(item: Item) -> bool:
         return query.match(item)
     else:
         return False
-
+
+
 def should_transcode(item, fmt):
     """Determine whether the item should be transcoded as part of
     conversion (i.e., its bitrate is high or it has the wrong format).

pyproject.toml

@@ -67,6 +67,9 @@ resampy = { version = ">=0.4.3", optional = true }
 requests-oauthlib = { version = ">=0.6.1", optional = true }
 soco = { version = "*", optional = true }
 
+pydata-sphinx-theme = { version = "*", optional = true }
+sphinx = { version = "*", optional = true }
+
 [tool.poetry.group.test.dependencies]
 beautifulsoup4 = "*"
 codecov = ">=2.1.13"
@@ -96,10 +99,6 @@ types-PyYAML = "*"
 types-requests = "*"
 types-urllib3 = "*"
 
-[tool.poetry.group.docs.dependencies]
-pydata-sphinx-theme = "*"
-sphinx = "*"
-
 [tool.poetry.group.release.dependencies]
 click = ">=8.1.7"
 packaging = ">=24.0"
@@ -115,6 +114,7 @@ beatport = ["requests-oauthlib"]
 bpd = ["PyGObject"] # python-gi and GStreamer 1.0+
 chroma = ["pyacoustid"] # chromaprint or fpcalc
 # convert # ffmpeg
+docs = ["pydata-sphinx-theme", "sphinx"]
 discogs = ["python3-discogs-client"]
 embedart = ["Pillow"] # ImageMagick
 embyupdate = ["requests"]

test/plugins/test_convert.py

@@ -18,12 +18,11 @@
 import re
 import sys
 import unittest
-import pytest
 
+import pytest
 from mediafile import MediaFile
 
 from beets import util
-from beetsplug import convert
 from beets.library import Item
 from beets.test import _common
 from beets.test.helper import (
@@ -34,6 +33,7 @@
     control_stdin,
 )
 from beets.util import bytestring_path, displayable_path
+from beetsplug import convert
 
 
 def shell_quote(text):
@@ -352,7 +352,6 @@ class TestNoConvert:
             ("bitrate:320 , format:ogg", True),
         ],
     )
-
     def test_no_convert_skip(self, config_value, should_skip):
         item = Item(format="ogg", bitrate=256)
         convert.config["convert"]["no_convert"] = config_value