docs: evaluate forward references

This is to get annotations in `TYPE_CHECKING` blocks to show.

docs/conf.py

@@ -10,19 +10,19 @@
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
 
-import build
-
 
 # -- Project information -----------------------------------------------------
 
+import importlib.metadata
+
 project = 'build'
 copyright = '2020, Filipe Laíns'
 author = 'Filipe Laíns'
 
 # The short X.Y version
-version = build.__version__
+version = importlib.metadata.version('build')
 # The full version, including alpha/beta/rc tags
-release = build.__version__
+release = version
 
 
 # -- General configuration ---------------------------------------------------
@@ -67,3 +67,5 @@
 autoclass_content = 'both'
 
 autodoc_preserve_defaults = True
+
+set_type_checking_flag = True

setup.cfg

@@ -46,6 +46,7 @@ pipx.run =
 
 [options.extras_require]
 docs =
+    build[typing]
     furo>=2021.08.31
     sphinx~=4.0
     sphinx-argparse-cli>=1.5