doc - Fix import error introduced by 1450a0c

* See: 1450a0c

Author: phibos

docs/source/conf.py

@@ -7,7 +7,6 @@
 import sys
 from pathlib import Path
 
-from overpy import __about__ as overpy_about
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
@@ -51,10 +50,15 @@
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 #
-# The short X.Y version.
-version = overpy_about.__version__
-# The full version, including alpha/beta/rc tags.
-release = overpy_about.__version__
+try:
+    from overpy import __about__ as overpy_about
+    # The short X.Y version.
+    version = overpy_about.__version__
+    # The full version, including alpha/beta/rc tags.
+    release = overpy_about.__version__
+except ImportError:
+    version = "unknown"
+    release = version
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.