Rust

Remove soroban-spec-tools (#80) #116

Job	Run time
fmt	12s
build-and-test (msrv)	3m 26s
build-and-test (latest)	2m 29s
rust-analyzer-compat	1m 39s
publish-dry-run (macos-latest, aarch64-apple-darwin, --feature-powerset) / publish-dry-run	3m 44s
publish-dry-run (macos-latest, x86_64-apple-darwin, --feature-powerset) / publish-dry-run	3m 17s
publish-dry-run (ubuntu-latest, aarch64-unknown-linux-gnu, --feature-powerset) / publish-dry-run	2m 58s
publish-dry-run (ubuntu-latest, x86_64-unknown-linux-gnu, --feature-powerset) / publish-dry-run	2m 17s
publish-dry-run (windows-latest-8-cores, x86_64-pc-windows-msvc, --features opt --ignore-unknown-... / publish-dry-run	3m 34s
publish-dry-run (windows-latest-8-cores, x86_64-pc-windows-msvc) / publish-dry-run	3m 58s
complete	1s
	27m 35s

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