Bump maven-compiler-plugin from 3.1 to 3.8.1 in /PgBulkInsert

Bumps [maven-compiler-plugin](https://github.com/apache/maven-compiler-plugin) from 3.1 to 3.8.1.
- [Release notes](https://github.com/apache/maven-compiler-plugin/releases)
- [Commits](apache/maven-compiler-plugin@maven-compiler-plugin-3.1...maven-compiler-plugin-3.8.1)

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

Author: dependabot-preview[bot]

PgBulkInsert/pom.xml

@@ -58,7 +58,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.1</version>
+                <version>3.8.1</version>
                 <configuration>
                     <source>1.8</source>
                     <target>1.8</target>