Change avro dependency scope to provided

[morazow]

Situation

The common project has avro as compile time dependency. This causes issues when user of the library wants to use the recent versions of the avro. We should set this dependency to the provided scope.

AC

• Dependency scope is changed

Reference

          Are these exclusions common to all projects using `import-export-udf-common-scala_*`?

If yes: does it make sense to add the exclusions to the upstream project?
At least slf4j-simple can be excluded without consequences.

Originally posted by @kaklakariada in exasol/kafka-connector-extension#70 (comment)