Remove old versions of Julia from CI

These won't work with the new `CodeInfo`, so it's pointless to run our
tests on them, for now. At some point it might make sense to make the
non-eval related parts of JuliaLowering work on older versions for use
by tooling packages, but it's unclear this is practical.

Author: c42f

.github/workflows/CI.yml

@@ -19,8 +19,6 @@ jobs:
       fail-fast: false
       matrix:
         version:
-          - '1.0'
-          - '1.11'
           - 'nightly'
         os:
           - ubuntu-latest