tests: Revert dropping of EPEL on RHEL

This was wrongly dropped in commit 168e0397aa. On RHEL/CentOS
installing chromium still needs some dependencies from EPEL.

tests/verify.sh

@@ -16,6 +16,11 @@ chmod a+w "$LOGS"
 # HACK: chromium 88 crashes with some keyDown commands: https://bugs.chromium.org/p/chromium/issues/detail?id=1170634
 if rpm -q chromium-headless; then
     dnf remove -y chromium-headless
+else
+    if grep -q 'ID=.*rhel' /etc/os-release; then
+        dnf install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
+        dnf config-manager --enable epel
+    fi
 fi
 
 if grep -q 'ID=.*rhel' /etc/os-release; then