Trac #32598: cvxopt selftest should rely on pytest, not nose

Currently, selftest of `cvxopt` rely on `nose`, which is broken
(see#32595). Upstream does not mention `nose` anymore and recommends to
use `pytest`, see https://cvxopt.org/install/index.html

URL: https://trac.sagemath.org/32598
Reported by: tmonteil
Ticket author(s): Thierry Monteil
Reviewer(s): Matthias Koeppe

build/pkgs/cvxopt/dependencies

@@ -1,4 +1,4 @@
-$(PYTHON) numpy $(BLAS) gsl glpk suitesparse | $(PYTHON_TOOLCHAIN) pkgconfig nose matplotlib
+$(PYTHON) numpy $(BLAS) gsl glpk suitesparse | $(PYTHON_TOOLCHAIN) pkgconfig matplotlib $(and $(filter-out no,$(SAGE_CHECK_cvxopt)), pytest)
 
 matplotlib is needed to test cvxopt (i.e., if SAGE_CHECK=yes). See #12742.
 

build/pkgs/cvxopt/spkg-check.in

@@ -1,8 +1,3 @@
 cd src
 
-if ! command -v nosetests ; then 
-    echo >&2 'Testing cvxopt requires the package nose to be installed'
-    exit 1
-fi
-
-nosetests
+pytest