osc: add failing test for osc 133 parsing trailing ;

This actually causes a crash lol, bad indexing of a slice with `1..0`
because it's `key.len + 1 ..` and the length is `0`.

src/terminal/osc/parsers/semantic_prompt.zig

@@ -348,6 +348,18 @@ test "OSC 133: prompt_start with special_key empty" {
     try testing.expect(cmd.prompt_start.special_key == false);
 }
 
+test "OSC 133: prompt_start with trailing ;" {
+    const testing = std.testing;
+
+    var p: Parser = .init(null);
+
+    const input = "133;A;";
+    for (input) |ch| p.next(ch);
+
+    const cmd = p.end(null).?.*;
+    try testing.expect(cmd == .prompt_start);
+}
+
 test "OSC 133: prompt_start with click_events true" {
     const testing = std.testing;