Bump pyspfm from 0.0.1b19 to 0.0.1b23

Bumps [pyspfm](https://github.com/Paradigm-Free-Mapping/pySPFM) from 0.0.1b19 to 0.0.1b23.
- [Release notes](https://github.com/Paradigm-Free-Mapping/pySPFM/releases)
- [Commits](Paradigm-Free-Mapping/pySPFM@v0.0.1-beta.19...v0.0.1-beta.23)

---
updated-dependencies:
- dependency-name: pyspfm
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -5,7 +5,7 @@ matplotlib
 myst_nb
 nitransforms
 repo2data==2.9.1
-pyspfm==0.0.1b19
+pyspfm==0.0.1b23
 seaborn
 sphinx>=4
 sphinx-inline-tabs