Remove now unnecessary JDK 16 specific workaround

Now that we are not using reflection anymore to push unsupported HTTP
methods, we can remove this workaround.

Author: gsmet

pom.xml

@@ -596,16 +596,6 @@
         </plugins>
       </build>
     </profile>
-    <profile>
-      <id>jdk11+</id>
-      <activation>
-        <jdk>[11,)</jdk>
-      </activation>
-      <properties>
-        <!-- this is required for GithubHttpUrlConnectionClient#setRequestMethod() to work with JDK 16+ -->
-        <surefire.argLine>--add-opens java.base/java.net=ALL-UNNAMED</surefire.argLine>
-      </properties>
-    </profile>
     <profile>
       <id>ci-non-windows</id>
       <activation>