CI: solaris: drop non-existent x11/library/libxt from pkg list

The FMRI does not exist in the OpenIndiana Hipster catalog (both the
old per-package loop and the new batched install failed on it; the
xserver does not link libXt, so the build succeeds without it). A
single unmatched FMRI aborts the whole IPS transaction, so leaving it
in broke the batched install and forced the per-package fallback.
Removing it lets the single pkg install transaction succeed.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

.github/scripts/solaris/install-pkg.sh

@@ -48,7 +48,6 @@ libs="
     x11/library/libxext
     x11/library/libxfixes
     x11/library/libxrender
-    x11/library/libxt
     x11/library/libx11
     x11/library/xtrans
     x11/library/libxkbfile