tests/float: Fix cmath_fun_special for MICROPY_FLOAT_IMPL_FLOAT.

When the unix and windows ports use MICROPY_FLOAT_IMPL_FLOAT instead of
MICROPY_FLOAT_IMPL_DOUBLE, the test output has for example
complex(-0.15052, 0.34109) instead of the expected
complex(-0.15051, 0.34109).

Use one decimal place less for the output printing to fix this.

tests/float/cmath_fun_special.py

@@ -29,4 +29,4 @@ for f_name, f, test_vals in functions:
     print(f_name)
     for val in test_vals:
         ret = f(val)
-        print("complex(%.5g, %.5g)" % (ret.real, ret.imag))
+        print("complex(%.4g, %.4g)" % (ret.real, ret.imag))