Close plot.py tests
Close plot.py tests

This avoids a warning from matplotlib about too many concurrent plots.

kaichogami/sympy,lindsayad/sympy,ChristinaZografou/sympy,chaffra/sympy,yashsharan/sympy,kaichogami/sympy,drufat/sympy,skidzo/sympy,postvakje/sympy,kaushik94/sympy,rahuldan/sympy,Titan-C/sympy,Titan-C/sympy,lindsayad/sympy,kaichogami/sympy,mafiya69/sympy,jaimahajan1997/sympy,madan96/sympy,kaushik94/sympy,hargup/sympy,ChristinaZografou/sympy,madan96/sympy,lindsayad/sympy,yashsharan/sympy,postvakje/sympy,Titan-C/sympy,rahuldan/sympy,jaimahajan1997/sympy,Curious72/sympy,mafiya69/sympy,madan96/sympy,aktech/sympy,yashsharan/sympy,postvakje/sympy,mafiya69/sympy,hargup/sympy,sampadsaha5/sympy,skidzo/sympy,souravsingh/sympy,aktech/sympy,drufat/sympy,Curious72/sympy,drufat/sympy,skidzo/sympy,ChristinaZografou/sympy,Curious72/sympy,aktech/sympy,kaushik94/sympy,jerli/sympy,rahuldan/sympy,chaffra/sympy,souravsingh/sympy,jerli/sympy,sampadsaha5/sympy,jaimahajan1997/sympy,chaffra/sympy,sampadsaha5/sympy,jerli/sympy,hargup/sympy,souravsingh/sympy