Install chromium only when rfbrowser init

[petschki]

As it is stated here

meta/README.md

Lines 176 to 178 in ed34dc8

	> [!TIP]
	> 🍀 `plone.meta` tries to be a bit more environmentally friendly.
	> On GitHub, only the first and last Python versions will be added for testing.

It would be even more environmental friendly if we install chromium only with rfbrowser init chromium 😉

[gforcada]

Oh, good point, I did not know that you could tweak which browsers get installed 👍🏾

Would you mind doing a patch for it?