Update release instructions to include bump_dev_version task

Author: kateinoigakukun

CONTRIBUTING.md

@@ -117,6 +117,7 @@ $ gh run download <run-id>
 $ for pkg in cross-gem/pkg/ruby_wasm-*; do gem push $pkg; done
 $ gem build && gem push ruby_wasm-*.gem && rm ruby_wasm-*.gem
 $ (cd packages/gems/js/ && gem build && gem push js-*.gem && rm js-*.gem)
+$ rake bump_dev_version
 ```
 
 ## Release Channels

lib/ruby_wasm/version.rb

@@ -1,3 +1,3 @@
 module RubyWasm
-  VERSION = "2.6.2"
+  VERSION = "2.6.2.dev"
 end

rakelib/version.rake

@@ -38,3 +38,17 @@ task :bump_version, %i[version] do |t, args|
   # Update Gemfile.lock
   sh "BUNDLE_GEMFILE=packages/npm-packages/ruby-wasm-wasi/Gemfile bundle install"
 end
+
+def bump_dev_version_rb(version_rb)
+  version_rb_content = File.read(version_rb)
+  version_rb_content.sub!(/VERSION = "(.+)"$/) do
+    dev_version = $1.end_with?(".dev") ? $1 : $1 + ".dev"
+    "VERSION = \"#{dev_version}\""
+  end
+  File.write(version_rb, version_rb_content)
+end
+
+task :bump_dev_version do
+  bump_dev_version_rb("lib/ruby_wasm/version.rb")
+  bump_dev_version_rb("packages/gems/js/lib/js/version.rb")
+end