Fix minimum version of depencency on Fluentd

Confirmed this did not work with Fluentd v1.8.1.

Signed-off-by: daipom <fukuda@clear-code.com>

Author: daipom

README.md

@@ -2,10 +2,10 @@
 
 [Fluentd](https://fluentd.org/) plugin to collect debug information of Fluentd.
 
- | Platform | Support Version       |
- | -------- | --------------------- |
- | Fluentd  | Fluentd v1.x          |
- | Ruby     | Ruby 2.7.x / 3.1.x    |
+ | Platform |  Support Version   |
+ |----------|--------------------|
+ | Fluentd  | >= Fluentd v1.9.3  |
+ | Ruby     | Ruby 2.7.x / 3.1.x |
 
 This plugin periodically dumps backtrace and memory profile of Fluentd by using [sigdump](https://github.com/fluent/sigdump).
 

fluent-plugin-sigdump.gemspec

@@ -19,5 +19,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency "test-unit", "~> 3.3"
 
   s.add_runtime_dependency "sigdump", "~> 0.2.2"
-  s.add_runtime_dependency "fluentd", [">= 0.14.10", "< 2"]
+  s.add_runtime_dependency "fluentd", [">= 1.9.3", "< 2"]
 end