Support Zig 0.12

[rupurt]

Currently there are build and test errors

╰─ zig build
/home/alex/workspace/mjoerussell/zig-odbc/build.zig:27:9: error: local variable is never mutated
    var lib = b.addStaticLibrary(.{
        ^~~
/home/alex/workspace/mjoerussell/zig-odbc/build.zig:27:9: note: consider using 'const'
/home/alex/workspace/mjoerussell/zig-odbc/build.zig:63:13: error: local variable is never mutated
        var current_tests = b.addTest(.{
            ^~~~~~~~~~~~~
/home/alex/workspace/mjoerussell/zig-odbc/build.zig:63:13: note: consider using 'const'

[rupurt]

I've made the const changes on a branch and the errors are now:

╰─ zig build test
/home/alex/workspace/mjoerussell/zig-odbc/build.zig:48:40: error: root struct of file 'std' has no member named 'build'
pub fn setupOdbcDependencies(step: *std.build.Step.Compile) void {
                                    ~~~^~~~~~
/nix/store/rlabnlq8gad6sx0jldlja54habc7gc4k-zig-0.12.0-dev.2644+42fcca49c/lib/std/std.zig:1:1: note: struct declared here
pub const ArrayHashMap = array_hash_map.ArrayHashMap;
^~~
referenced by:
    build: /home/alex/workspace/mjoerussell/zig-odbc/build.zig:33:5
    runBuild__anon_8964: /nix/store/rlabnlq8gad6sx0jldlja54habc7gc4k-zig-0.12.0-dev.2644+42fcca49c/lib/std/Build.zig:1982:27
    remaining reference traces hidden; use '-freference-trace' to see all reference traces