Bump tolerance in calculus tests

Apparently rounding errors have changed in Julia-1.11, so the tolerance
for one of the calculus tests needs to be relaxed slightly.

moment_kinetics/test/calculus_tests.jl

@@ -701,7 +701,7 @@ function runtests()
                     # something like p*(round-off) for x^p (?) so error on expected_df would
                     # be p*p*(round-off), or plausibly 1024*(round-off), so tolerance of
                     # 2e-11 isn't unreasonable.
-                    @test isapprox(df, expected_df, rtol=2.0e-11, atol=6.0e-12,
+                    @test isapprox(df, expected_df, rtol=3.0e-11, atol=6.0e-12,
                                    norm=maxabs_norm)
                 end
             end