tests: drivers: gpio-async: Add testcase.yaml

Create this, to restrict to the tiny2040 platform.  As this platform is
not in Zephyr, this should avoid the tests actually ever running.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

tests/drivers/gpio-async/testcase.yaml

@@ -0,0 +1,13 @@
+common:
+  filter: CONFIG_RUST_SUPPORTED
+  platform_allow:
+    - pimoroni_tiny2040
+tests:
+  test.gpio-async:
+    harness: console
+    harness_config:
+      type: one_line
+      regex:
+        # This doesn't actually happen, as this test requires specific hardware and buttons to be
+        # pressed.
+        - "All tests passed"