Update to use Fedora 35 from Eclipse CBI and Maven 3.8.3

Change-Id: Ic33c58d81c2e693b43c83277ffb480cbb36a1de9
Reviewed-on: https://git.eclipse.org/r/c/linuxtools/org.eclipse.linuxtools.eclipse-build/+/187607
Tested-by: Alexander Kurtakov <akurtako@redhat.com>
Reviewed-by: Alexander Kurtakov <akurtako@redhat.com>
diff --git a/flatpak-dockerfiles/Dockerfile b/flatpak-dockerfiles/Dockerfile
index bdc55e0..ad42890 100644
--- a/flatpak-dockerfiles/Dockerfile
+++ b/flatpak-dockerfiles/Dockerfile
@@ -1,7 +1,7 @@
 # We basically just need a Linux with Flatpak >= 1.7.1
 # So it can be based on any Fedora or CentOS/RHEL >= 8.4 when it is released
 
-FROM eclipsecbi/fedora:33
+FROM eclipsecbi/fedora:35
 
 # Install flatpak tools
 RUN yum -y install flatpak flatpak-builder
@@ -12,7 +12,7 @@
 RUN yum clean all
 
 # Install maven
-ENV MAVEN_VERSION 3.6.3
+ENV MAVEN_VERSION 3.8.3
 RUN curl -fsSL http://archive.apache.org/dist/maven/maven-3/$MAVEN_VERSION/binaries/apache-maven-$MAVEN_VERSION-bin.tar.gz | tar xzf - -C /usr/share \
   && mv /usr/share/apache-maven-$MAVEN_VERSION /usr/share/maven \
   && ln -s /usr/share/maven/bin/mvn /usr/bin/mvn