Version not showed in --version parameter

[gjrlopes]

I'm submitting a ...

• bug report
• feature request

What is the current behavior?

Empty application version.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

What is the expected behavior?

Version filled.
Update main.Version to github.com/prometheus/common/version.Version in Makefile

What is the motivation / use case for changing the behavior?

Please tell us about your environment:

Version: 0.6.0
https://github.com/iamseth/oracledb_exporter/releases/download/0.6.0/oracledb_exporter.tar.gz

[Yannig]

Thanks for the report!
I will take a look