Fix confluent repository URL

[rhum1-sakharov]

To fix the error below :

Could not resolve dependencies for project com.github.simplesteph.udemy.kafka:kafka-avro-v2:jar:1.0-SNAPSHOT: The following artifacts could not be resolved: io.confluent:kafka-avro-serializer:jar:3.1.1, io.confluent:kafka-schema-registry-client:jar:3.1.1, io.confluent:common-config:jar:3.1.1, io.confluent:common-utils:jar:3.1.1: Could not transfer artifact io.confluent:kafka-avro-serializer:jar:3.1.1 from/to maven-default-http-blocker (http://0.0.0.0/): Blocked mirror for repositories: [confluent (http://packages.confluent.io/maven/, default, releases+snapshots)] 

Needed to change the confluent repository url with https on all pom.xml :

    <!--necessary to resolve confluent dependencies-->
    <repositories>
        <repository>
            <id>confluent</id>
            <url>https://packages.confluent.io/maven/</url>
        </repository>
    </repositories>