Revert "Temporarily remove grass from Qt 5 CI"

This reverts commit b3cdf9e.

With the ubuntugis ppa removed, grass can now be installed.

Author: ptitjano

.docker/qgis3-qt5-build-deps.dockerfile

@@ -166,6 +166,7 @@ FROM binary-for-oracle as binary-only
 
 RUN  apt-get update \
   && DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    grass \
     iproute2 \
     postgresql-client \
     spawn-fcgi \
@@ -200,6 +201,7 @@ RUN  apt-get update \
     clang \
     cmake \
     flex \
+    grass-dev \
     libdraco-dev \
     libexiv2-dev \
     libexpat1-dev \