copr: separate describe-isntances filters with a space instead of a comma

Fixing the following issue

    Error parsing parameter '--filters': Second instance of key "Name" encountered for input:
    Name=tag-key,Values=Name,Name=tag-value,Values=copr-dev-builder-x86_64-20201212_122038_399669659
			    ^
    This is often because there is a preceeding "," instead of a space.

roles/copr/backend/files/copr-builder-image-prepare-cloud.sh

@@ -96,7 +96,7 @@ EOF
 elif test $cloud = aws; then
     instance_id=$(aws ec2 describe-instances \
         --query "Reservations[].Instances[].InstanceId" \
-        --filter Name=tag-key,Values=Name,Name=tag-value,Values="$vm_name" \
+        --filter Name=tag-key,Values=Name Name=tag-value,Values="$vm_name" \
         --output text
     )