chore(ci): change dependabot schedule and add grouping #1795

Job	Run time
check / cargo check	3m 30s
check / commit messages	2s
check / cargo clippy	3m 49s
check / cargo test docs	4m 39s
check / cargo sort	16s
check / cargo fmt	14s
check / cargo machete	20s
build and test macOS-aarch64	3m 19s
build Windows	5m 27s
build and test Linux-x86_64-musl	9m 2s
Code coverage	0s
Backwards compatibility / check_commit_message	4s
Backwards compatibility / build_and_test	2m 5s
finalize_pr	1s
	32m 48s

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