gst-examples: correct upstream version check

If start-of-line is not enforced, then bogus tag 'gstreamer-sharp-1.13.0.1' would
match as 13.0.1.

(From OE-Core rev: 094cbd4f6a9f57eb146207355a921eaae44012ab)

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-multimedia/gstreamer/gst-examples_1.26.2.bb

@@ -18,7 +18,7 @@ S = "${WORKDIR}/git/subprojects/gst-examples"
 
 inherit meson pkgconfig features_check
 
-UPSTREAM_CHECK_GITTAGREGEX = "(?P<pver>\d+\.(\d*[02468])+(\.\d+)+)"
+UPSTREAM_CHECK_GITTAGREGEX = "^(?P<pver>\d+\.(\d*[02468])+(\.\d+)+)"
 
 ANY_OF_DISTRO_FEATURES = "${GTK3DISTROFEATURES}"