Install LLVM 13 on Ubuntu

[keynmol]

Previously, on ubuntu the clang version we built with was 10, which was failing linkage on even my linux box, which is not super new, but only has LLVM versions from 11 to 13.

I've confirmed that the new version is linked against newer libclang and as such works on my machine:

❯ ldd ~/Desktop/bindgen-out
        linux-vdso.so.1 (0x00007fff4030a000)
        libclang-13.so.13 => /lib/x86_64-linux-gnu/libclang-13.so.13 (0x00007ff795412000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007ff79540d000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ff795408000)
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007ff7951ef000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007ff79510b000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007ff7950f1000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ff794ec7000)
        libLLVM-13.so.1 => /lib/x86_64-linux-gnu/libLLVM-13.so.1 (0x00007ff78f2e3000)
        /lib64/ld-linux-x86-64.so.2 (0x00007ff79736b000)
        libffi.so.8 => /lib/x86_64-linux-gnu/libffi.so.8 (0x00007ff78f2d7000)
        libedit.so.2 => /lib/x86_64-linux-gnu/libedit.so.2 (0x00007ff78f29e000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007ff78f282000)
        libtinfo.so.6 => /lib/x86_64-linux-gnu/libtinfo.so.6 (0x00007ff78f251000)
        libxml2.so.2 => /lib/x86_64-linux-gnu/libxml2.so.2 (0x00007ff78f06f000)
        libbsd.so.0 => /lib/x86_64-linux-gnu/libbsd.so.0 (0x00007ff78f057000)
        libicuuc.so.67 => /lib/x86_64-linux-gnu/libicuuc.so.67 (0x00007ff78ee6d000)
        liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007ff78ee42000)
        libmd.so.0 => /lib/x86_64-linux-gnu/libmd.so.0 (0x00007ff78ee33000)
        libicudata.so.67 => /lib/x86_64-linux-gnu/libicudata.so.67 (0x00007ff78d31a000)

This is the binary I downloaded from the last build of this job.