Bump minimal php requirement to 7.3

[adamturcsan]

Used dependency (ie. laminas/laminas-dependency-plugin) already requires this

[adamturcsan]

If there's anything else that needs to be changed for php:^7.3 I'll try to follow.

There are quite old dependencies that could be updated also if php7.2 support is not required. I'll look into it, if necessary, but honestly I just want to push for a release to use this with up-to-date environment ASAP.

[adamturcsan]

Ok, so it didn't caught my attention that the 2.1.0 tag was already made(packagist crawler hasn't noticed it either), so now I could use the lib if packagist notices 👍
But the CI is still failing, the php:^7.2 requirement is still false, so here it is :)

[RWOverdijk]

You're right, that was messy of me. Thanks for this.

[adamturcsan]

Ehm, could you tell me, why haven't you merged this?
2.1.0...2.1.1 It shows no changes :( I assume the CI will also fail (it recieved a job for 7.2)

[RWOverdijk]

I thought I did hit merge... Chaotic day.

[adamturcsan]

The point is we sorted it out. Thank you! :)