Relax check for probabilities in MarkovianGraph

[odow]

Overlooked cases with rounding error:

julia> sum(fill(1 / 9, 9))
1.0000000000000002

[codecov]

Codecov Report

Merging #322 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #322   +/-   ##
=======================================
  Coverage   94.02%   94.02%           
=======================================
  Files          21       21           
  Lines        1706     1706           
=======================================
  Hits         1604     1604           
  Misses        102      102           

Impacted Files	Coverage Δ
src/user_interface.jl	98.38% <100.00%> (ø)
src/plugins/parallel_schemes.jl	92.68% <0.00%> (-1.22%)	⬇️
src/modeling_aids.jl	100.00% <0.00%> (+1.72%)	⬆️

---

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 2761f5d...8f3cbdd. Read the comment docs.