gems: update async requirement from ~> 1.31.0 to >= 1.31, < 2.35

Updates the requirements on [async](https://github.com/socketry/async) to permit the latest version.
- [Release notes](https://github.com/socketry/async/releases)
- [Changelog](https://github.com/socketry/async/blob/main/releases.md)
- [Commits](https://github.com/socketry/async/compare/v1.31.0...v2.34.0)

---
updated-dependencies:
- dependency-name: async
  dependency-version: 2.34.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/vulnscan.yml

@@ -1,10 +1,9 @@
-# yaml-language-server: $schema=https://json.schemastore.org/github-workflow.json
 ---
 name: vulnscan
 
 on:
   schedule:
-  - cron: '7 4 * * 4'  # weekly on thursday morning
+  - cron: '7 4 1 * *'  # monthly on first day's morning
   workflow_dispatch:
 
 jobs:

docker/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.22.1
+FROM alpine:3.22.2
 
 EXPOSE 5353 8080
 

docker/ci/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.22.1
+FROM alpine:3.22.2
 
 EXPOSE 5353 8080
 

dyndnsd.gemspec

@@ -27,7 +27,7 @@ Gem::Specification.new do |s|
 
   s.required_ruby_version = '>= 3.0'
 
-  s.add_dependency 'async', '~> 1.31.0'
+  s.add_dependency 'async', '>= 1.31', '< 2.35'
   s.add_dependency 'async-dns', '~> 1.3.0'
   s.add_dependency 'base64', '~> 0.2.0' # needed for async
   s.add_dependency 'logger', '>= 1.6', '< 1.8'