Merge #551: Remove rust-version from workspace manifest

771277e Remove rust-version from workspace manifest (Tobin C. Harding)

Pull request description:

  During the `cargo rbmt` re-write of CI we accidentally added `rust-version` to the workspace manifest. This is a per-crate setting and doesn't live here.

  This does show up on master but as a warning not an error

  ```bash
  just lint
  $REPO_DIR/contrib/lint-verify.sh
  ++ git rev-parse --show-toplevel
  + REPO_DIR=/home/tobin/build/corepc
  ++ cat ./nightly-version
  + cargo +nightly-2025-09-12 clippy --manifest-path /home/tobin/build/corepc/verify/Cargo.toml --config ./rustfmt.toml --all-targets --all-features -- --deny warnings
  warning: unused manifest key: workspace.rust-version
  ```

ACKs for top commit:
  jamillambert:
    ACK 771277e
  satsfy:
    ACK 771277e
  luisschwab:
    ACK 771277e

Tree-SHA512: 2865e2edc810d0d8562264c12c717190a7509704d6695fc671a0c362f87bedc2f4e47ea8d6dd4b8f7db0abeac0021a905cbab79b8b21683340b4ef753ca3e4b2

Author: tcharding

Cargo.toml

@@ -2,7 +2,6 @@
 members = ["bitcoind", "bitreq", "client", "fuzz", "jsonrpc", "types"]
 exclude = ["integration_test", "verify", "electrsd"]
 resolver = "2"
-rust-version = "1.75.0"
 
 [workspace.metadata.rbmt.toolchains]
 nightly = "nightly-2025-09-12"