ci: disable dependabot cargo updates #708

Job	Run time
Ktlint	35s
Clippy (-Zbuild-std)	36s
Clippy (stable) (ubuntu-latest)	47s
Clippy (MSRV) (ubuntu-latest)	3m 19s
Clippy (stable) (macos-latest)	30s
Clippy (MSRV) (macos-latest)	3m 11s
Check for documentation errors	20s
Clippy (stable) (windows-latest)	53s
Rustfmt	8s
Clippy (MSRV) (windows-latest)	3m 59s
Test (ubuntu-latest)	12s
Test (Android)	3m 45s
Test (FreeBSD)	3m 13s
Test (macos-latest)	17s
Test (windows-latest)	1m 24s
Verify Android artifacts	1m 4s
	24m 13s

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