Fix evalutating expressions including percentage operator(modulo with…

[jarkonik]

… arity == 1)

It caused crashes in /lib/dentaku/ast/operation.rb:14:in `dependencies' for expressions like 5%

[codecov-io]

Codecov Report

Merging #167 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #167      +/-   ##
==========================================
+ Coverage   96.18%   96.19%   +0.01%     
==========================================
  Files          53       53              
  Lines        1338     1342       +4     
==========================================
+ Hits         1287     1291       +4     
  Misses         51       51

Impacted Files	Coverage Δ
lib/dentaku/ast/arithmetic.rb	95.23% <100%> (+0.18%)	⬆️

---

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 3c190a5...2f2ee1c. Read the comment docs.

[rubysolo]

Thank you!