Fix: Drop support for PHP 7.1, 7.2, and 7.3

[localheinz]

What is the reason for this PR?

• drop support for outdated PHP versions
• runs make baseline

Author's checklist

• Follow the Contribution Guide
• New features and changes are documented

Summary of changes

Dropping support for outdated PHP versions, see https://www.php.net/supported-versions.php.

Review checklist

• All checks have passed
• Changes are approved by maintainer

[bram-pkg]

This sounds like a good change. Technically don't have to wait for 2.0 for this, since I don't think composer will update past the version constraints.

[bram-pkg]

For some reason the bcroave check is failing?

[localheinz]

@bram-pkg

Build failure seems unrelated to me, not sure what the problem is.

@Nyholm

Since we use https://github.com/Nyholm/roave-bc-check-docker here, can you take a look, please?

[localheinz]

@bram-pkg

Opened an issue at Nyholm/roave-bc-check-docker#32.

[GrahamCampbell]

I don't see much value in this, especially given we're not using any new features. I'd recommend we hold off here for a bit, or maybe go with a less aggressive bump to 7.2.5 as the minimum.

[localheinz]

@GrahamCampbell

Where do you see value in supporting outdated PHP versions?

[GrahamCampbell]

Where there is little or no effort, it is more effort to drop support than to do nothing.

[GrahamCampbell]

I also still use PHP 7 myself...

[GrahamCampbell]

I could be amenable to going with ^7.4 || ^8.0, though.

[bram-pkg]

I think supporting 7.4 is reasonable still, since the previous Laravel version still supports 7.4.

[localheinz]

Thank you, @bram-pkg and @GrahamCampbell!