Enable parallel tests (#117)

src/test/resources/junit-platform.properties

@@ -0,0 +1,25 @@
+#
+# Copyright 2023 Creek Contributors (https://github.com/creek-service)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+junit.jupiter.execution.parallel.enabled = true
+junit.jupiter.execution.parallel.mode.default = concurrent
+junit.jupiter.execution.parallel.mode.classes.default = concurrent
+junit.jupiter.execution.parallel.config.strategy = fixed
+# GitHub's runners only have two cores:
+# https://docs.github.com/en/actions/using-github-hosted-runners/about-github-hosted-runners#supported-runners-and-hardware-resources
+junit.jupiter.execution.parallel.config.fixed.parallelism = 2
+junit.jupiter.execution.parallel.config.fixed.max-pool-size = 4
+