build: fix error message for wrong zig version

previously:
```
[I] ➜  ghostty git:(main) /opt/homebrew/bin/zig build -Demit-macos-app=false
/opt/homebrew/Cellar/zig/0.15.1/lib/zig/std/Io/Writer.zig:1198:9: error: ambiguous format string; specify {f} to call format method, or {any} to skip it
        @CompileError("ambiguous format string; specify {f} to call format method, or {any} to skip it");
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/homebrew/Cellar/zig/0.15.1/lib/zig/std/Io/Writer.zig:700:25: note: called at comptime here
        try w.printValue(
            ~~~~~~~~~~~~^
/opt/homebrew/Cellar/zig/0.15.1/lib/zig/std/fmt.zig:629:20: note: called at comptime here
    dw.writer.print(fmt, args) catch |err| switch (err) {
    ~~~~~~~~~~~~~~~^~~~~~~~~~~
/opt/homebrew/Cellar/zig/0.15.1/lib/zig/std/fmt.zig:658:83: note: called at comptime here
pub inline fn comptimePrint(comptime fmt: []const u8, args: anytype) *const [count(fmt, args):0]u8 {
                                                                             ~~~~~^~~~~~~~~~~
src/build/zig.zig:12:44: note: generic function instantiated here
        @CompileError(std.fmt.comptimePrint(
                      ~~~~~~~~~~~~~~~~~~~~~^
build.zig:7:24: note: called at comptime here
    buildpkg.requireZig("0.14.0");
    ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~
referenced by:
    root: /opt/homebrew/Cellar/zig/0.15.1/lib/zig/compiler/build_runner.zig:17:26
    main: /opt/homebrew/Cellar/zig/0.15.1/lib/zig/compiler/build_runner.zig:366:30
    4 reference(s) hidden; use '-freference-trace=6' to see all references
src/build/GhosttyResources.zig:16:47: error: struct 'array_list.Aligned(*Build.Step,null)' has no member named 'init'
    var steps = std.ArrayList(*std.Build.Step).init(b.allocator);
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
/opt/homebrew/Cellar/zig/0.15.1/lib/zig/std/array_list.zig:606:12: note: struct declared here
    return struct {
           ^~~~~~
```

Author: recursiveforte

src/build/zig.zig

@@ -10,8 +10,8 @@ pub fn requireZig(comptime required_zig: []const u8) void {
         current_vsn.minor != required_vsn.minor)
     {
         @compileError(std.fmt.comptimePrint(
-            "Your Zig version v{} does not meet the required build version of v{}",
-            .{ current_vsn, required_vsn },
+            "Your Zig version {s} does not meet the required build version of {s}",
+            .{ builtin.zig_version_string, required_zig },
         ));
     }
 }