CI: Update solc version being tested with nix shell

Author: blishko

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
           nix develop .# --command -- bash -c "solc-0.8.33 --version"
 
           # test `nix shell`
-          nix shell .#solc_0_8_19
+          nix shell .#solc_0_8_33
 
           # test solc.nix as input to other flakes
           # Note: overriding flake input is needed as a workaround to local sub flake with overlapping paths.