Prepare vault-storage for JitPack with Java 17 and Central Portal Snapshots

- Add jitpack.yml to specify Java 17 for JitPack builds
- Bump version to 1.3.18-grails7-upgrade-test
- JitPack will now build with:
  - Java 17 (from jitpack.yml)
  - rundeck-core:6.0.0-SNAPSHOT from Central Portal Snapshots
- Tested successfully with sshj-plugin v0.1.23

Author: fdevans

build.gradle

@@ -24,7 +24,7 @@ ext.rundeckPluginVersion= '1.2'
 ext.pluginClassNames='io.github.valfadeev.rundeck.plugin.vault.VaultStoragePlugin'
 
 // Override version for Grails 7 upgrade (bump to 1.3.17)
-project.version = '1.3.17-grails7-upgrade-test'
+project.version = '1.3.18-grails7-upgrade-test'
 
 repositories {
     mavenLocal()

jitpack.yml

@@ -0,0 +1,2 @@
+jdk:
+  - openjdk17