Fix the plot_implicit warning test
Fix the plot_implicit warning test

The warning uses the spelling labelled instead of labeled.

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