Fix compilation errors caused by usage of make_unique on elder compilers

[Mr-Question]

[codecov-io]

Codecov Report

Merging #3 into master will not change coverage. The diff coverage is 100%.

@@           Coverage Diff           @@
##           master       #3   +/-   ##
=======================================
  Coverage   99.32%   99.32%           
=======================================
  Files           9        9           
  Lines         742      742           
=======================================
  Hits          737      737           
  Misses          5        5

Impacted Files	Coverage Δ
include/MyGAL/FortuneAlgorithm.h	100% <100%> (ø)	:arrow_up:

---

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 cfe5afc...c04efc6. Read the comment docs.