chore: configure kcov for test coverage

src/Story/runtime_tests.zig

@@ -1,6 +1,6 @@
 const std = @import("std");
 const fatal = std.process.fatal;
-const ink = @import("root.zig");
+const ink = @import("../root.zig");
 
 const Options = struct {
     input_reader: *std.Io.Reader,

src/root.zig

@@ -6,5 +6,5 @@ test {
     _ = tokenizer;
     _ = Ast;
     _ = Story;
-    _ = @import("runtime_tests.zig");
+    _ = @import("Story/runtime_tests.zig");
 }