Replace pkg_resources with packaging for version parsing (#206)

`pkg_resources` from `setuptools` is unavailable in Python 3.13,
breaking the docs build with Sphinx 9. This switches to the `packaging`
library which provides the same `Version.base_version` API and is the
modern standard replacement. Also drops the stale `markupsafe==2.0.1`
pin which was a workaround for an old Jinja2 compatibility issue.

Author: manzt

docs/build.py

@@ -2,8 +2,7 @@
 # requires-python = ">=3.12"
 # dependencies = [
 #     "higlass-python",
-#     "markupsafe==2.0.1",
-#     "setuptools",
+#     "packaging",
 #     "sphinx-js",
 #     "Sphinx",
 # ]

docs/conf.py

@@ -4,7 +4,7 @@
 
 from docutils import nodes
 from docutils.parsers.rst import Directive, directives
-from pkg_resources import parse_version
+from packaging.version import Version
 
 from higlass import __version__
 
@@ -70,7 +70,7 @@
 # built documents.
 #
 # The short X.Y version.
-version = parse_version(__version__).base_version
+version = Version(__version__).base_version
 # The full version, including alpha/beta/rc tags.
 release = __version__