Enable further multiple estimation syntax tests against `fixest`

[leostimpfle]

Enable these tests now that lrberge/fixest#631 is fixed:

pyfixest/tests/test_vs_fixest.py

Lines 965 to 989 in ba99e35

	# TODO: enable once fixest bug is fixed, see https://github.com/lrberge/fixest/issues/631
	pytest.param(
	"Y ~ X1 | sw0(f1, f1+f2)",
	marks=pytest.mark.skip(reason="fixest nparams bug (#631)"),
	),
	pytest.param(
	"Y ~ X1 | csw0(f1, f1+f2)",
	marks=pytest.mark.skip(reason="fixest nparams bug (#631)"),
	),
	pytest.param(
	"Y ~ X1 | sw(f1, f1+f2)",
	marks=pytest.mark.skip(reason="fixest nparams bug (#631)"),
	),
	pytest.param(
	"Y ~ X1 | sw0(f1, f1+f2, f1+f2+f3)",
	marks=pytest.mark.skip(reason="fixest nparams bug (#631)"),
	),
	pytest.param(
	"Y ~ X1 | csw0(f1, f1+f2, f1+f2+f3)",
	marks=pytest.mark.skip(reason="fixest nparams bug (#631)"),
	),
	pytest.param(
	"Y ~ X1 | mvsw(f1, f2)",
	marks=pytest.mark.skip(reason="fixest nparams bug (#631)"),
	),