Upgrade maven-compiler-plugin 3.8.1 -> 3.10.1 (#62)

And drop the redundant `--source` and `--target` flags.

See:
- https://github.com/apache/maven-compiler-plugin/releases/tag/maven-compiler-plugin-3.9.0
- https://github.com/apache/maven-compiler-plugin/releases/tag/maven-compiler-plugin-3.10.0
- https://github.com/apache/maven-compiler-plugin/releases/tag/maven-compiler-plugin-3.10.1
- apache/maven-compiler-plugin@maven-compiler-plugin-3.8.1...maven-compiler-plugin-3.10.1

pom.xml

@@ -722,7 +722,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
-                    <version>3.8.1</version>
+                    <version>3.10.1</version>
                     <configuration>
                         <annotationProcessorPaths>
                             <path>
@@ -739,12 +739,6 @@
                         </compilerArgs>
                         <parameters>true</parameters>
                         <release>${version.jdk}</release>
-                        <!-- Even though `-release X` implies `-source X` and
-                        `-target X`, we need to configure these properties
-                        explicitily, for otherwise the plugin's default value
-                        of `1.6` is passed on. -->
-                        <source>${version.jdk}</source>
-                        <target>${version.jdk}</target>
                         <!-- Erroneously inverted logic... for details, see
                         https://issues.apache.org/jira/browse/MCOMPILER-209. -->
                         <useIncrementalCompilation>false</useIncrementalCompilation>