Upgrade Maven to 3.9.6 (#1774)

Due to removal of HTTP support on Maven Central

Remove JDK 6 build since now unsupported by Maven

.github/workflows/main.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java: ['6', '8', '11', '17', '18']
+        java: ['8', '11', '17', '18']
     steps:
       - uses: actions/checkout@v2
       - name: Download Maven # Download with default JDK because OpenJDK 6 does not support TLS 1.2

.mvn/wrapper/maven-wrapper.properties

@@ -1 +1,18 @@
-distributionUrl=https://repo1.maven.org/maven2/org/apache/maven/apache-maven/3.1.1/apache-maven-3.1.1-bin.zip
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+wrapperVersion=3.3.1
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.6/apache-maven-3.9.6-bin.zip