c72069e921 Bump MSRV to 1.63 (Martin Habovstiak)
Pull request description:
The version 1.63 satisfies our requirements for MSRV and provides significant benefits so this commit bumps it. This commit also starts using some advantages of the new MSRV, namely namespaced features, weak dependencies and the ability to use trait bounds in `const` context.
This however does not yet migrade the `rand-std` feature because that requires a release of `secp256k1` with the same kind of change - bumping MSRV to 1.63 and removing `rand-std` in favor of weak dependency. (Accompanying PR to secp256k1: https://github.com/rust-bitcoin/rust-secp256k1/pull/709 )
Suggested plan:
* merge both PRs
* at some point release `hashes` and `secp256k`
* remove `rand-std` from `bitcoin`
* release the rest of the crates
ACKs for top commit:
apoelstra:
ACK c72069e921
tcharding:
ACK c72069e921
Tree-SHA512: 0b301ef8145f01967318d3ed1c738d33e6cf9e44f835f3762122b460a536f926916dbd6ea39d6f80b4f95402cd845e924401e75427dbb0731ca5b12b4fa6915e