Remove asdf as an optional dependency

Author: ViciousEagle03

ndcube/asdf/converters/tests/test_ndcube_converter.py

@@ -1,5 +1,7 @@
 import numpy as np
 import pytest
+from gwcs import __version__ as gwcs_version
+from packaging.version import Version
 
 import asdf
 
@@ -13,6 +15,7 @@
                                 ("ndcube_gwcs_3d_rotated"),
                                 ("ndcube_gwcs_4d_ln_lt_l_t")
                                 ], indirect=("ndc",))
+@pytest.mark.skipif(Version(gwcs_version) < Version("0.20"), reason="Requires gwcs>=0.20")
 def test_serialization(ndc, tmp_path):
     file_path = tmp_path / "test.asdf"
     with asdf.AsdfFile() as af:

pyproject.toml

@@ -53,16 +53,11 @@ plotting = [
 reproject = [
   "reproject>=0.7.1",
 ]
-asdf = [
-  "asdf>=2.14.4",
-  "astropy>=5.3.0",
-  "gwcs>=0.20"
-]
 all = [
-  "ndcube[plotting,reproject,asdf]",
+  "ndcube[plotting,reproject]",
 ]
 dev = [
-  "ndcube[tests,docs,plotting,reproject,asdf]",
+  "ndcube[tests,docs,plotting,reproject]",
 ]
 [project.urls]
 repository = "https://docs.sunpy.org/projects/ndcube"

tox.ini

@@ -63,7 +63,6 @@ deps =
     figure-!devdeps: dask
 # The following indicates which extras_require will be installed
 extras =
-    asdf
     plotting
     reproject
     tests