Merge branch '6-fix-check-links' into 'master'

fix: specifiy user agent to fix check links issue on mend.io

Closes #6

See merge request to-be-continuous/renovate!15

lychee.toml

+
+#############################  Requests  ############################
+
+# User agent to send with each request.
+user_agent = "Mozilla/version Gecko/version Firefox/version"