Add Dependabot configuration for GitHub Actions #4093

Job	Run time
checks / pre-commit	32s
checks / readme-snippets	12s
checks / test (3.10, highest, ubuntu-latest)	45s
checks / test (3.10, lowest-direct, windows-latest)	2m 15s
checks / test (3.10, highest, windows-latest)	2m 39s
checks / test (3.11, lowest-direct, ubuntu-latest)	43s
checks / test (3.11, highest, windows-latest)	2m 38s
checks / test (3.14, highest, windows-latest)	2m 25s
checks / test (3.13, highest, windows-latest)	2m 33s
checks / test (3.12, highest, ubuntu-latest)	48s
checks / test (3.10, lowest-direct, ubuntu-latest)	47s
checks / test (3.13, lowest-direct, ubuntu-latest)	45s
checks / test (3.12, lowest-direct, ubuntu-latest)	50s
checks / test (3.14, lowest-direct, windows-latest)	2m 18s
checks / test (3.11, lowest-direct, windows-latest)	2m 31s
checks / test (3.14, highest, ubuntu-latest)	1m 12s
checks / test (3.13, lowest-direct, windows-latest)	2m 24s
checks / test (3.13, highest, ubuntu-latest)	42s
checks / test (3.11, highest, ubuntu-latest)	45s
checks / test (3.12, highest, windows-latest)	3m 17s
checks / test (3.12, lowest-direct, windows-latest)	3m 16s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 18s
	35m 35s

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