Don't bother signing with GPG

We have never signed `maxmind-db` and no one has complained.

I believe this configuration may be broken with the most recent version
of Maven anyway.

Author: oschwald

pom.xml

@@ -179,20 +179,6 @@
                     </execution>
                 </executions>
             </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-gpg-plugin</artifactId>
-                <version>3.2.7</version>
-                <executions>
-                    <execution>
-                        <id>sign-artifacts</id>
-                        <phase>verify</phase>
-                        <goals>
-                            <goal>sign</goal>
-                        </goals>
-                    </execution>
-                </executions>
-            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>