print version to stdout when -version flag is used

[ethanmdavidson]

otherwise, print it to stderr as normal.

fixes #646

[coveralls]

Pull Request Test Coverage Report for Build 1578

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 92.09%

---

Totals
Change from base Build 1576:	0.0%
Covered Lines:	1793
Relevant Lines:	1947

---

💛 - Coveralls

[codecov]

Codecov Report

Merging #662 (20f47e4) into master (3a74303) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #662   +/-   ##
=======================================
  Coverage   88.15%   88.15%           
=======================================
  Files          16       16           
  Lines        1941     1941           
=======================================
  Hits         1711     1711           
  Misses        154      154           
  Partials       76       76           

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[oliver006]

Thank you!

[oliver006]

Released as https://github.com/oliver006/redis_exporter/releases/tag/v1.41.0

[nkn1111]

Thank you so much @ethanmdavidson @oliver006