Adds ktexttemplate as apt package to new_docker_build.sh and builds successfully

qt6-after/qt6-migrated-legatus/Lts/Common/CodeGen/svc_dtc_impl.cpp.grantlee

@@ -215,7 +215,7 @@ bool DtcImpl::waitForHistoricalData{{ dt.name }}(int timeoutMSec)
 template <>
 {{ dt.key.cppType }} getKey(const {{ dt.type }} &val)
 {
-  return val.{{ dt.key.name }}();
+  return val.{{ dt.key.name }};
 }
 
 QMap<{{ dt.key.cppType }},::{{ namespace }}::{{ dt.type }}> DtcImpl::{{ dt.nameFlc }}s()