Improve error message when = is used instead of == (#3892) #4743

	name: format-check
	on:
	push:
	branches:
	- master
	- release-*
	pull_request:
	types: [opened, synchronize, reopened]
	jobs:
	build:
	runs-on: ubuntu-latest
	steps:
	- uses: julia-actions/setup-julia@latest
	with:
	version: '1'
	- uses: actions/checkout@v4
	- name: Format check
	shell: julia --color=yes {0}
	run: \|
	using Pkg
	# If you update the version, also update the style guide docs.
	Pkg.add(PackageSpec(name="JuliaFormatter", version="1"))
	using JuliaFormatter
	format("src", verbose=true)
	format("test", verbose=true)
	format("docs", verbose=true)
	out = String(read(Cmd(`git diff`)))
	if isempty(out)
	exit(0)
	end
	@error "Some files have not been formatted !!!"
	write(stdout, out)
	exit(1)

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