Bump version for v0.13.1 release #181

Job	Run time
Lint & mypy	17s
Test & build (py3.12 on ubuntu-latest)	14s
Test & build (py3.11 on ubuntu-latest)	13s
Test & build (py3.10 on ubuntu-latest)	19s
Test & build (py3.9 on ubuntu-latest)	16s
Test & build (py3.8 on ubuntu-latest)	17s
Test & build (py3.7 on ubuntu-latest)	12s
Test & build (py3.12 on windows-latest)	45s
Test & build (py3.11 on windows-latest)	31s
Test & build (py3.10 on windows-latest)	29s
Test & build (py3.9 on windows-latest)	42s
Test & build (py3.8 on windows-latest)	42s
Test & build (py3.7 on windows-latest)	45s
Test & build (py3.12 on macos-latest)	31s
Test & build (py3.11 on macos-latest)	16s
Test & build (py3.10 on macos-latest)	27s
Test & build (py3.9 on macos-latest)	22s
Test & build (py3.8 on macos-latest)	17s
Test & build (py3.7 on macos-latest)	20s
	7m 55s

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