[pre-commit.ci] auto fixes from pre-commit hooks

Author: pre-commit-ci[bot]

README.rst

@@ -180,4 +180,4 @@ Acknowledgements
 ``diffpy.srfit`` is built and maintained with `scikit-package <https://scikit-package.github.io/scikit-package/>`_.
 
 The source code in *observable.py* was derived from the 1.0 version
-of the Caltech "Pyre" project.
+of the Caltech "Pyre" project.