Pin dependencies in CI for MSRV build

Recently the MSRV build broke. We can pin the dependencies in the MSRV
CI job.

Pin `log` and `rustls` when running the MSRV CI job.

Author: tcharding

.github/workflows/cont_integration.yml

@@ -48,6 +48,9 @@ jobs:
       run: rustup component add clippy
     - name: Update toolchain
       run: rustup update
+    - name: pin dependencies
+      if: ${{ matrix.rust.version }} == 1.57.0
+      run: cargo update -p log --precise 0.4.18 && cargo update -p rustls@0.21.2 --precise 0.21.1
     - name: Build
       run: cargo build --features ${{ matrix.features }} --no-default-features
     - name: Clippy