Added php 7.4

[BhawaniSingh]

What does this PR do?

Added php 7.4

What issues does this PR fix or reference?

Symphony demo doesn't work with php 7.1

Previous behavior

(Remove this section if not relevant)

New behavior

(Explain the PR as it should appear in the release notes)

Please review Che's Contributing Guide for best practices.

Tests written?

No

Docs updated?

Please add a matching PR to the docs repo and link that PR to this issue. Both will be merged at the same time.

[JPinkney]

@BhawaniSingh You'll need to sign the eclipse contributor agreement and sign your commit and then I can merge this PR and fix the sample!

[BhawaniSingh]

I tried to sign the ECA, but I'm facing issue,

Anonymous (BhawaniSingh@****.noreply) is not covered by the necessary legal agreements in order to proceed.

It was because my email set to private in github, even though I changed my mail to public, I'm still seeing this issue.
Can you help me out with this one?

[sparkoo]

@BhawaniSingh I think you have to sign the commit. You must have git config user.name and user.email set to same ones as you have registered on eclipse. Then do the commit with --signoff

https://wiki.eclipse.org/Development_Resources/Contributing_via_Git#Signing_off_on_a_commit