fix: hard-code khisto version

Otherwise, Sphinx cannot find the khisto package metadata, because
khisto itself is not installed.

TODO: Use this version in pyproject.toml itself as well.

Author: popescu-v

src/khisto/__init__.py

@@ -14,7 +14,7 @@
 
 KHISTO_BIN_DIR = os.environ.get("KHISTO_BIN_DIR", "khisto")
 
-__version__ = version("khisto")
+__version__ = "0.1.0"
 
 from .array import histogram  # noqa: E402
 from .core import HistogramResult  # noqa: E402