PHP: The mirror repository used to host protobuf for packagist has not been synced

[dwsupplee]

This is causing an issue with installations via composer, as it is allowing PHP 5.5/5.6 to install versions such as v3.20.0 which actually require PHP >=7.0.

For example, due to the inclusion of return type hinting:

PHP Parse error:  syntax error, unexpected ':', expecting ';' or '{' in /tmpfs/src/github/google-cloud-php/vendor/google/protobuf/src/Google/Protobuf/Internal/RepeatedField.php on line 240

[bshaffer]

cc @haberman
Unfortunately this one is breaking anyone using protobuf on < PHP 7.0. This is because the latest versions say they support PHP 5.5 but they're actually only compatible with PHP 7+.

We need to fix composer.json to be correct and then remove those tags (because composer will always pull them in for PHP 5.5 / 5.6 even after we fix composer.json because they will be seen as the latest compatible versions of this library for those PHP versions).

Until we do that, protobuf will be completely broken for anyone on PHP 5.5 and 5.6

[perezd]

@haberman is this something that we missed as part of a release step?

[bshaffer]

I am submitting googleapis/gax-php#382 to exclude the broken version of protobuf until we can get this resolved

[bshaffer]

We are also looking at php/release.sh, because this doesn't seem to be getting called

[haberman]

I think the underlying problem was fixed in #9832 (with a related fix in #9819).

Separately, we need to yank the 3.20.0 release since it advertises compatibility with PHP 5.5 but is not actually compatible.