Bump ehcache from 3.9.3 to 3.9.4 (#1949)

Bumps [ehcache](https://github.com/ehcache/ehcache3) from 3.9.3 to 3.9.4.
- [Release notes](https://github.com/ehcache/ehcache3/releases)
- [Commits](ehcache/ehcache3@v3.9.3...v3.9.4)

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metrics-jcache/pom.xml

@@ -19,7 +19,7 @@
     <properties>
         <javaModuleName>com.codahale.metrics.jcache</javaModuleName>
         <cache-api.version>1.1.1</cache-api.version>
-        <ehcache3.version>3.9.3</ehcache3.version>
+        <ehcache3.version>3.9.4</ehcache3.version>
     </properties>
 
     <dependencyManagement>