Update phpspec/phpspec to 7.3

[dannyvw]

Q	A
Bug fix?	no
New feature?	no
BC breaks?	no
Deprecations?	no
Related tickets	fixes #X, partially #Y, mentioned in #Z
License	MIT

[lchrusciel]

Hey Danny,

thanks a lot for proposal. Can you fix psalm and ping me on slack to have it merged?

In the meantime, I've changed the branch, so it can land quicker into the release

[lchrusciel]

The base of this pull-request was changed, you need fetch and reset your local branch
if you want to add new commits to this pull request. Reset before you pull, else commits
may become messed-up.

Unless you added new commits (to this branch) locally that you did not push yet,
execute git fetch origin && git reset "phpspec" to update your local branch.

Feel free to ask for assistance when you get stuck 👍