Add Dependabot with monthly groups #113

Job	Run time
windows (windows-latest, x64)	2m 1s
linux (ubuntu-latest, x86_64)	1m 29s
windows (windows-latest, x86)	2m 16s
pytest (3.11)	39s
musllinux (ubuntu-latest, aarch64)	2m 52s
coverage	31s
sdist	10s
linux (ubuntu-latest, aarch64)	5m 19s
linux (ubuntu-latest, x86)	1m 50s
musllinux (ubuntu-latest, x86_64)	1m 16s
pytest (3.14)	29s
macos (macos-14, aarch64)	39s
pytest (3.13)	34s
pytest (3.12)	35s
musllinux (ubuntu-latest, x86)	1m 20s
pytest (3.10)	40s
Release	-1s
	22m 39s

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