Global `symfony/flex` is not needed

symfony/flex is already added to composer.json

Line 29 in 0ff22b5

"symfony/flex": "^2.0",

So, I think this action is not required.

Lines 58 to 59 in 0ff22b5

    
           - name: "Require symfony/flex" 
        
             run: composer global require --no-progress --no-scripts --no-plugins symfony/flex

The action will also produce an unnecessary error

Btw, why run composer update instead of composer install?

demo/.github/workflows/tests.yaml

Line 61 in 0ff22b5

- run: composer update

The global symfony/flex dependency was removed in #1373.

About using composer update instead of composer install ... since we only test one specific Symfony version, I guess we could use install. If anyone wants to send a Pull Request for this change, please do it. Thanks.

	- name: "Require symfony/flex"
	run: composer global require --no-progress --no-scripts --no-plugins symfony/flex