BLD: Set astropy oldest supported version to 5.0 (#660)

Author: rrjbca

tox.ini

@@ -3,7 +3,7 @@ envlist =
     py{39,310,311,312,313}-test{,-all}{,-dev,-latest,-oldest}{,-cov}
     py{39,310,311,312,313}-test-numpy{121,122,123,124,125,126,20,21,22,23,24}
     py{39,310,311,312,313}-test-scipy{18,19,110,111,112,113,114,115,116,117}
-    py{39,310,311,312,313}-test-astropy{43,50,51,52,53,60,61,70,71,72}
+    py{39,310,311,312,313}-test-astropy{50,51,52,53,60,61,70,71,72}
     build_docs
     linkcheck
     codestyle
@@ -57,7 +57,6 @@ description =
     scipy115: with scipy 1.15.*
     scipy116: with scipy 1.16.*
     scipy117: with scipy 1.17.*
-    astropy43: with astropy 4.3.*
     astropy50: with astropy 5.0.*
     astropy51: with astropy 5.1.*
     astropy52: with astropy 5.2.*
@@ -94,7 +93,6 @@ deps =
     scipy116: scipy==1.16.*
     scipy117: scipy==1.17.*
 
-    astropy43: astropy==4.3.*
     astropy50: astropy==5.0.*
     astropy51: astropy==5.1.*
     astropy52: astropy==5.2.*
@@ -113,7 +111,7 @@ deps =
     latest: numpy==2.4.*
     latest: scipy==1.17.*
 
-    oldest: astropy==4.3.*
+    oldest: astropy==5.0.*
     oldest: numpy==1.21.*
     oldest: scipy==1.8.*