CI: test a matrix of Credo version

[mhanberg]

Description

credo-language-server should work with many versions of Credo, and our CI suite should ensure that.

[wesleimp]

Do you have in mind what versions we should use?

[mhanberg]

Probably the latest patch release of all minor versions since 1.0 and the lastest of the default branch

• master
• 1.0.5
• 1.1.5
• 1.2.3
• 1.3.1
• 1.4.1
• 1.5.6
• 1.6.7
• 1.7.0