Add googletest as prereq for RHEL docker build

Author: d-torrance

M2/BUILD/docker/rhel/Dockerfile

@@ -17,7 +17,7 @@ RUN dnf install -y 'dnf-command(config-manager)' && \
 # Install dependencies
 RUN dnf -y install autoconf automake bison boost-devel bzip2 cmake     \
     diffutils eigen3 flex gc-devel gcc-c++ gcc-gfortran gdbm-devel git \
-    glpk-devel gmp-devel lapack-devel libffi-devel libtool             \
+    glpk-devel gmp-devel gtest-devel lapack-devel libffi-devel libtool \
     libxml2-devel make mpfr-devel ncurses-devel openblas-devel patch   \
     python3-devel R readline-devel rpm-build tbb-devel which xz-devel  \
     zlib-devel