Update dependency golang to v1.21.5 #184

	name: Go
	on: [push]
	jobs:

	test:
	name: Build
	runs-on: ubuntu-latest
	strategy:
	matrix:
	go: [ '1.21.x' ]
	steps:

	- name: Set up Go
	uses: actions/setup-go@v4
	with:
	go-version: ${{ matrix.go }}
	id: go

	- name: Check out code into the Go module directory
	uses: actions/checkout@v4

	- name: test
	run: \|
	make vet
	make test
	make bin/notify_slack

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