Fix: bring back missing 'release' mode to the build config

[miredirex]

Previous commit that changed this line: https://github.com/tiltedphoques/TiltedEvolution/commit/a94f7168666b831a6b0447121307453fc23a05a8#diff-1e65723e47b81d67c25a98980a10861a012068422521d2331e559e547a4e79ccL11

Release .exe now builds just fine and the size is smaller