fixed incompatibility with pandas 0.25 update

[jaumebonet]

No description provided.

[codecov]

Codecov Report

Merging #5 into master will increase coverage by 0.04%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master       #5      +/-   ##
==========================================
+ Coverage   95.84%   95.89%   +0.04%     
==========================================
  Files           3        3              
  Lines         265      268       +3     
==========================================
+ Hits          254      257       +3     
  Misses         11       11

Impacted Files	Coverage Δ
libconfig/evaluator.py	100% <100%> (ø)	⬆️

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[codecov]

Codecov Report

Merging #5 into master will increase coverage by 0.04%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master       #5      +/-   ##
==========================================
+ Coverage   95.84%   95.89%   +0.04%     
==========================================
  Files           3        3              
  Lines         265      268       +3     
==========================================
+ Hits          254      257       +3     
  Misses         11       11

Impacted Files	Coverage Δ
libconfig/evaluator.py	100% <100%> (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 9b34cef...72641e7. Read the comment docs.

[coveralls]

Pull Request Test Coverage Report for Build 72

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.05%) to 95.896%

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Totals
Change from base Build 70:	0.05%
Covered Lines:	257
Relevant Lines:	268

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💛 - Coveralls