ci: build on rust 1.91 — the locked Arti 0.46 crates require rustc >= 1.91

The rust:1.87-bookworm job image failed every builder step with
'tor-*@0.46.0 requires rustc 1.91 ... either upgrade rustc or select
compatible dependency versions'. Cargo.toml declared rust-version 1.87,
which was simply wrong: cargo 1.87 could not even resolve the lockfile.

- rust-version 1.87 -> 1.91 (README requirement text too)
- RUST_IMAGE rust:1.87-bookworm -> rust:1.91-bookworm in ci and release

.forgejo/workflows/ci.yml

@@ -10,7 +10,7 @@ on:
 
 env:
   CARGO_TERM_COLOR: never
-  RUST_IMAGE: rust:1.87-bookworm
+  RUST_IMAGE: rust:1.91-bookworm
   CARGO_REGISTRY_VOLUME: onionwire-cargo-registry
   CARGO_TARGET_VOLUME: onionwire-target-ci
   BUILD_CONTAINER: onionwire-ci

.forgejo/workflows/release.yml

@@ -19,7 +19,7 @@ env:
   TARGET: aarch64-unknown-linux-gnu
   # Job steps run inside node:20-bullseye (the runner's docker label image) with
   # the host docker socket mounted, so builds happen in a sibling rust container.
-  RUST_IMAGE: rust:1.87-bookworm
+  RUST_IMAGE: rust:1.91-bookworm
   CARGO_REGISTRY_VOLUME: onionwire-cargo-registry
   CARGO_TARGET_VOLUME: onionwire-target-aarch64
   BUILD_CONTAINER: onionwire-release-build

Cargo.toml

@@ -2,7 +2,7 @@
 name = "onionwire"
 version = "0.1.2"
 edition = "2024"
-rust-version = "1.87"
+rust-version = "1.91"
 description = "Lean Tor messenger: Arti in-process, identity=pubkey, onion=locator. No XMPP."
 license = "MIT"
 publish = false

README.md

@@ -58,13 +58,13 @@ Checksum files are `sha256sum` format (`<hash>  onionwire-<target>`). Download b
 
 ### Option B — build from source
 
-Needs [Rust](https://rustup.rs/) **1.87+** (`edition = "2024"`). A distro `rustc` is fine if `rustc --version` reports 1.87 or newer. Do not install `tor` for this app.
+Needs [Rust](https://rustup.rs/) **1.91+** (`edition = "2024"`; the pinned Arti 0.46 crates require rustc 1.91). A distro `rustc` is fine if `rustc --version` reports 1.91 or newer. Do not install `tor` for this app.
 
 ```bash
 # rustup (if you do not already have cargo)
 curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
 source "$HOME/.cargo/env"
-rustc --version   # must be 1.87 or newer
+rustc --version   # must be 1.91 or newer
 ```
 
 ```bash
@@ -203,7 +203,7 @@ FORGEJO_TOKEN=<pat> scripts/build-release-local.sh vX.Y.Z
 ```
 
 Workflows (Forgejo Actions, `.forgejo/workflows/` — jobs run on the `docker`
-label of the Pi runner and do their Rust work in a `rust:1.87-bookworm`
+label of the Pi runner and do their Rust work in a `rust:1.91-bookworm`
 sibling container):
 
 - [`.forgejo/workflows/ci.yml`](.forgejo/workflows/ci.yml) — `cargo test --locked` + `cargo clippy --all-targets -- -D warnings` on `main` and PRs (ignored Tor-live tests are not run).