Upgrade llvm 18 zig 13

[lukewilliamboswell]

@Anton-4 -- not urgent, just making a note while I'm looking at this

We need to update the following in CI workflows to use zig 13.

      - name: Update PATH to use zig 11
        run: |
          echo "PATH=/home/big-ci-user/Downloads/zig-linux-x86_64-0.11.0:$PATH" >> $GITHUB_ENV

I also think we should start using ROC_ZIG environment variable somehow, I don't see it in any of the CI scripts. Could we make this change against our current main, or would this be better in this PR?

[Anton-4]

I also think we should start using ROC_ZIG environment variable somehow, I don't see it in any of the CI scripts. Could we make this change against our current main, or would this be better in this PR?

New PR on main sounds good!

[lukewilliamboswell]

We should merge #6859 first before this PR.

[Anton-4]

Failure on nix x64 linux is the same as here: https://github.com/roc-lang/roc/pull/6859#issuecomment-2379437104

[lukewilliamboswell]

On my ubuntu x64 nix machine, cargo test --release fails with this.

I think we need to update the flake.nix to provide this dependency clang.

---- glue_cli_tests::single_tag_union stdout ----
thread 'glue_cli_tests::single_tag_union' panicked at crates/cli_test_utils/src/command.rs:82:9:
Command failed

Command: /home/lb-dev/Documents/Github/roc/target/release/roc dev /home/lb-dev/Documents/Github/roc/crates/glue/tests/fixtures/single-tag-union/app.roc --build-host --suppress-build-host-warning --linker=legacy

Exit Code: exit status: 101

Stdout:

Stderr:
🔨 Building host ...
thread '<unnamed>' panicked at crates/utils/command/src/lib.rs:79:9:
I could not find the clang command.
Please install clang.
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread 'main' panicked at crates/compiler/build/src/program.rs:841:58:
Failed to build host.: Any { .. }

[Anton-4]

Thanks for the review @folkertdev :heart:

[Anton-4]

I'll take care of the conflicts