increase the max flaky runs of test_balancing_learner

Author: basnijholt

adaptive/tests/test_learners.py

@@ -514,7 +514,7 @@ def scale_x(x):
     assert math.isclose(learner.loss(), control.loss(), rel_tol=1e-10)
 
 
-@flaky.flaky(max_runs=5)
+@flaky.flaky(max_runs=10)
 @run_with(
     Learner1D,
     Learner2D,