Merge pull request #356 from domaframework/snapshot

[Gradle Release Plugin] - new version commit:  '2.28.5-SNAPSHOT'.

Author: nakamura-to

gradle.properties

@@ -1,5 +1,5 @@
 group=org.seasar.doma
-version=2.28.4
+version=2.28.5-SNAPSHOT
 projectUrl=https://github.com/domaframework/doma
 githubUrl[email protected]:domaframework/doma.git
 sonatypeUrl=https://oss.sonatype.org/service/local/staging/deploy/maven2/