gio/tests/tls-certificates: fix
gio/tests/tls-certificates: fix

da053e34 broke the tls-certificates test by requiring the backend to
implement g_tls_certificate_verify() (which the test TLS backend
didn't). Add a trivial implementation to make the test pass again;
we'll need something more complicated when we add tests that are
supposed to get errors.

endlessm/glib,krichter722/glib,johne53/MB3Glib,ieei/glib,MathieuDuponchelle/glib,gale320/glib,ieei/glib,lukasz-skalski/glib,tamaskenez/glib,cention-sany/glib,Distrotech/glib,johne53/MB3Glib,ieei/glib,gale320/glib,tchakabam/glib,MathieuDuponchelle/glib,tamaskenez/glib,Distrotech/glib,cention-sany/glib,Distrotech/glib,johne53/MB3Glib,ieei/glib,endlessm/glib,lukasz-skalski/glib,gale320/glib,Distrotech/glib,cention-sany/glib,johne53/MB3Glib,krichter722/glib,lukasz-skalski/glib,endlessm/glib,MathieuDuponchelle/glib,endlessm/glib,cention-sany/glib,tamaskenez/glib,mzabaluev/glib,johne53/MB3Glib,mzabaluev/glib,tchakabam/glib,gale320/glib,tchakabam/glib,cention-sany/glib,tchakabam/glib,tamaskenez/glib,mzabaluev/glib,tchakabam/glib,ieei/glib,lukasz-skalski/glib,MathieuDuponchelle/glib,MathieuDuponchelle/glib,gale320/glib,lukasz-skalski/glib,tamaskenez/glib,krichter722/glib,krichter722/glib,krichter722/glib,johne53/MB3Glib,endlessm/glib,mzabaluev/glib,mzabaluev/glib,Distrotech/glib