Isolate old rustc version tests from needing anyhow dev-dependencies in lockfile

Otherwise:

    error: failed to select a version for the requirement `syn = "^2.0.87"`
    candidate versions found which didn't match: 2.0.56, 2.0.55, 2.0.54, ...
    location searched: crates.io index
    required by package `thiserror-impl v2.0.0`
        ... which satisfies dependency `thiserror-impl = "=2.0.0"` of package `thiserror v2.0.0`
        ... which satisfies dependency `thiserror = "^2"` of package `anyhow v1.0.92`

Author: dtolnay

.github/workflows/ci.yml

@@ -63,9 +63,9 @@ jobs:
         with:
           toolchain: ${{matrix.rust}}
           components: rust-src
-      - run: cargo check
-      - run: cargo check --no-default-features
-      - run: cargo check --features backtrace
+      - run: cargo check --manifest-path tests/crate/Cargo.toml
+      - run: cargo check --manifest-path tests/crate/Cargo.toml --no-default-features
+      - run: cargo check --manifest-path tests/crate/Cargo.toml --features backtrace
         if: matrix.rust != '1.65.0' && matrix.rust != '1.52.0' && matrix.rust != '1.51.0' && matrix.rust != '1.50.0' && matrix.rust != '1.39.0'
 
   minimal:

tests/crate/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "anyhow_test"
+version = "0.0.0"
+authors = ["David Tolnay <dtolnay@gmail.com>"]
+edition = "2018"
+publish = false
+
+[lib]
+path = "test.rs"
+
+[dependencies]
+anyhow = { path = "../..", default-features = false }
+
+[features]
+default = ["std"]
+std = ["anyhow/std"]
+backtrace = ["anyhow/backtrace"]

tests/crate/test.rs

@@ -0,0 +1,3 @@
+#![no_std]
+
+pub use anyhow::*;