test: try to get GVL tests to pass on macos and windows in CI

- add one more sync to avoid deadlock on macos/windows in CI
- lower the expected loop count, it's much lower on macos and windows
  than on linux for some reason.

test/test_integration_pending.rb

@@ -116,16 +116,16 @@ def test_busy_timeout
   end
 
   [
-    # 10 is the theoretical max if timeout is 100ms and active thread sleeps 10ms
-    # in practice this number is almost always 9, but let's leave a bit of room for randomness
-    {name: "test_busy_handler_timeout_releases_gvl", busy_handler_timeout: 100, expected_count: [:>=, 8]},
+    # 20 is the theoretical max if timeout is 100ms and active thread sleeps 10ms
+    # in CI, macos and windows systems seem to really not thread very well, so let's set a low non-zero bar
+    {name: "test_busy_handler_timeout_releases_gvl", busy_handler_timeout: 100, expected_count: [:>=, 3]},
 
     # in practive this number is almost always 0, but it might squeak in 1 if the timing is juuuust right
     {name: "test_busy_timeout_does_not_release_gvl", busy_timeout: 100, expected_count: [:<=, 1]}
   ].each do |test_case|
     define_method test_case[:name] do
       if test_case[:busy_handler_timeout]
-        @db.busy_handler_timeout = 100
+        @db.busy_handler_timeout = 200
       end
       if test_case[:busy_timeout]
         @db.busy_timeout = test_case[:busy_timeout]
@@ -160,6 +160,7 @@ def test_busy_timeout
           sync.send_to_main :ready
           busy.lock
         end
+        sync.send_to_main :done
       ensure
         db2&.close
       end
@@ -173,9 +174,10 @@ def test_busy_timeout
       end
       t1sync.send_to_thread :end
 
-      assert_operator(count, *test_case[:expected_count])
-
       busy.unlock
+      t2sync.wait_for_thread :done
+
+      assert_operator(count, *test_case[:expected_count])
     ensure
       active_thread&.join
       blocking_thread&.join