Add test for recent bugfix

tests/samples/adw_breakpoint_template.blp

@@ -0,0 +1,10 @@
+using Gtk 4.0;
+using Adw 1;
+
+template $MyTemplate {
+  Adw.Breakpoint {
+    setters {
+      template.some-prop: true;
+    }
+  }
+}

tests/samples/adw_breakpoint_template.ui

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+DO NOT EDIT!
+This file was @generated by blueprint-compiler. Instead, edit the
+corresponding .blp file and regenerate this file with blueprint-compiler.
+-->
+<interface>
+  <requires lib="gtk" version="4.0"/>
+  <template class="MyTemplate">
+    <child>
+      <object class="AdwBreakpoint">
+        <setter object="MyTemplate" property="some-prop">true</setter>
+      </object>
+    </child>
+  </template>
+</interface>

tests/test_samples.py

@@ -176,6 +176,7 @@ class TestSamples(unittest.TestCase):
             REQUIRE_ADW_1_5 = ["adw_alertdialog_responses"]
 
             SKIP_RUN = [
+                "adw_breakpoint_template",
                 "expr_closure",
                 "expr_closure_args",
                 "parseable",