CI: fix MSRV problems

Author: msrd0

.github/workflows/rust.yml

@@ -64,6 +64,10 @@ jobs:
           cargo -Z minimal-versions update
           cargo update --precise 1.3.0 lazy_static
           cargo update tracing
+          # there is a version of time w/o itoa, 0.3.42, which the solver prefers, but
+          # which is just too new for our current MSRV
+          cargo update itoa@1
+          cargo update --precise 0.3.41 [email protected]
         if: matrix.rust.name == 'MSRV'
       - uses: dtolnay/rust-toolchain@master
         with:
@@ -119,6 +123,7 @@ jobs:
             ~/.cargo/registry
             target
           key: "${{runner.os}} Rust ${{steps.rust-toolchain.outputs.cachekey}} (clippy)"
+      - run: cargo --config 'resolver.incompatible-rust-versions="fallback"' update
       - run: cargo clippy --workspace --profile test -- -Dclippy::all
 
   rustfmt: