ci: add dependabot #243

Job	Run time
build_asan	2m 55s
build (ubuntu-latest, 3.12.0, false)	58s
build (ubuntu-latest, 3.12.0, true)	29s
build (ubuntu-latest, 3.11.6, false)	24s
build (ubuntu-latest, 3.11.6, true)	31s
build (ubuntu-latest, 3.10.11, false)	22s
build (ubuntu-latest, 3.10.11, true)	28s
build (ubuntu-latest, 3.8.17, false)	22s
build (ubuntu-latest, 3.8.17, true)	19s
build (ubuntu-20.04, 3.6.8, false)	16s
build (ubuntu-20.04, 3.6.8, true)	24s
build (ubuntu-latest, pypy-3.7, false)	26s
build (ubuntu-latest, pypy-3.7, true)	27s
build (macos-latest, 3.12.0, false)	1m 16s
build (macos-latest, 3.11.6, false)	58s
build (macos-latest, 3.10.11, false)	50s
build (macos-latest, 3.8.17, false)	51s
build (macos-latest, 3.6.8, false)	41s
build (macos-latest, pypy-3.7, false)	31s
build (windows-latest, 3.12.0, false)	2m 20s
build (windows-latest, 3.11.6, false)	2m 19s
build (windows-latest, 3.10.11, false)	1m 20s
build (windows-latest, 3.8.10, false)	1m 9s
build (windows-latest, 3.6.8, false)	1m 53s
build (windows-latest, pypy-3.7, false)	1m 38s
	24m 7s

Provide feedback