Update required fluentd version to 1.7.0

* fluentd v0.12 support is already dropped as of v2.0.0
* To resolve required tzinfo version, fluentd v1.7.0 or later is
  required

Signed-off-by: Takuro Ashie <ashie@clear-code.com>

Author: ashie

fluent-plugin-sql.gemspec

@@ -16,7 +16,7 @@ Gem::Specification.new do |gem|
   gem.require_paths = ['lib']
   gem.license = "Apache-2.0"
 
-  gem.add_dependency "fluentd", [">= 0.12.17", "< 2"]
+  gem.add_dependency "fluentd", [">= 1.7.0", "< 2"]
   gem.add_dependency 'activerecord', "~> 6.1"
   gem.add_dependency 'activerecord-import', "~> 1.0"
   gem.add_development_dependency "rake", ">= 0.9.2"