Bump pitest-maven from 1.6.3 to 1.6.4

Bumps [pitest-maven](https://github.com/hcoles/pitest) from 1.6.3 to 1.6.4.
- [Release notes](https://github.com/hcoles/pitest/releases)
- [Commits](hcoles/pitest@1.6.3...1.6.4)

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -609,7 +609,7 @@
                     <plugin>
                         <groupId>org.pitest</groupId>
                         <artifactId>pitest-maven</artifactId>
-                        <version>1.6.3</version>
+                        <version>1.6.4</version>
                         <configuration>
                             <jvmArgs>
                                 <jvmArg>${additional.argLine}</jvmArg>