Linter fixes

Co-authored-by: David O'Sullivan <31728678+pivotal-david-osullivan@users.noreply.github.com>

Author: joushx

lib/java_buildpack/framework/dynatrace_one_agent.rb

@@ -202,7 +202,7 @@ def skip_errors?
       end
 
       def enable_fips?
-        credentials[ENABLE_FIPS] == "true"
+        credentials[ENABLE_FIPS] == 'true'
       end
 
       def tenanttoken(manifest)