ci: Fix MSRV build by precisely specifying some deps.

.github/workflows/ci.yaml

@@ -33,6 +33,14 @@ jobs:
       - uses: Swatinem/rust-cache@v2
         name: Load dependencies from cache
 
+      - name: Fix dep versions for MSRV
+        if: ${{ matrix.rust == '1.64.0' }}
+        run: |
+          cargo update -p clap --precise 4.3.24 # 4.4 moves to msrv 1.70
+          cargo update -p clap_lex --precise 0.5.0 # 0.5.1 moves to msrv 1.70 in a patch release
+          cargo update -p anstyle --precise 1.0.2 # 1.0.3 moves to msrv 1.70 in a patch release
+          cargo update -p regex --precise 1.9.6 # 1.10 moves to msrv 1.65
+
       - name: Build with stable features
         run: cargo build --features stable