By upgrading prometheus/client_model, several test functions had to be re-written due to 2 breaking changes made in protobuf when parsing messages to text:
1. '<' and '>' characters were replaced with '{' and '}' respectively.
2. The text format is non-deterministic. More information in https://github.com/golang/protobuf/issues/1121
Signed-off-by: Arthur Silva Sens <arthur.sens@coralogix.com>