fluentd-plugin: call gsub for strings only (#1475)

* Use gsub only for string variables

* Delete version change

fluentd/fluent-plugin-grafana-loki/fluent-plugin-grafana-loki.gemspec

@@ -6,7 +6,7 @@ Gem::Specification.new do |spec|
   spec.name    = 'fluent-plugin-grafana-loki'
   spec.version = '1.2.5'
   spec.authors = %w[woodsaj briangann cyriltovena]
-  spec.email   = ['awoods@grafana.com', 'brian@grafana.com' , 'cyril.tovena@grafana.com']
+  spec.email   = ['awoods@grafana.com', 'brian@grafana.com', 'cyril.tovena@grafana.com']
 
   spec.summary       = 'Output plugin to ship logs to a Grafana Loki server'
   spec.description   = 'Output plugin to ship logs to a Grafana Loki server'

fluentd/fluent-plugin-grafana-loki/lib/fluent/plugin/out_loki.rb

@@ -195,7 +195,7 @@ module Fluent
         data_labels = {} if data_labels.nil?
         data_labels = data_labels.merge(@extra_labels)
         # sanitize label values
-        data_labels.each { |k, v| formatted_labels[k] = v.gsub('"', '\\"') if v }
+        data_labels.each { |k, v| formatted_labels[k] = v.gsub('"', '\\"') if v && v&.is_a?(String) }
         formatted_labels
       end