Use a logger warning otherwise it's not displayed properly.

[ewjoachim]

Also move the warning to the correct location

Successful PR Checklist:

• Tests (units, integration, 100% coverage)
  • (not applicable?)
• Documentation
  • (not applicable?)
• Had a good time contributing?

[codecov]

Codecov Report

Merging #200 (6d6fbad) into master (a458826) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #200   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           13        13           
  Lines          980       979    -1     
  Branches       128       128           
=========================================
- Hits           980       979    -1     

Impacted Files	Coverage Δ
vault_cli/client.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update a458826...6d6fbad. Read the comment docs.