chore(ci): change dependabot schedule and add grouping #1796

Job	Run time
check / cargo clippy	3m 49s
check / commit messages	8s
check / cargo check	3m 24s
check / cargo test docs	4m 19s
check / cargo fmt	16s
check / cargo sort	16s
check / cargo machete	14s
build Windows	5m 24s
build and test macOS-aarch64	4m 58s
build and test Linux-x86_64-musl	6m 36s
Code coverage	0s
Backwards compatibility / check_commit_message	6s
Backwards compatibility / build_and_test	1m 44s
finalize_pr	1s
	31m 15s

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