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

@@ -87,7 +87,7 @@
         <plugin>
           <groupId>org.pitest</groupId>
           <artifactId>pitest-maven</artifactId>
-          <version>1.6.3</version>
+          <version>1.6.4</version>
         </plugin>
         <plugin>
           <groupId>org.sonarsource.scanner.maven</groupId>