Revert "update.sh: Prune tags if removed on remote"

This reverts commit 39034fbc4d.
Revert because --prune-tags not available on git version 2.11

update.sh

@@ -9,7 +9,7 @@ fi
 PREFIX=release;
 CONF_SCRIPT="configure.sh";
 
-git fetch --tags --prune-tags > /dev/null;
+git fetch --tags > /dev/null;
 TAG=$(git tag --list | grep "^$PREFIX-" | sort -r | head -n 1);
 if git verify-tag --raw "$TAG" 2>&1 | grep "TRUST_ULTIMATE" > /dev/null; then
     git checkout -q "$TAG";