Add correct header/footer to junit xml output

[melven]

This adds the following lines to the begin/end of the xml output:

<?xml version="1.0" encoding="UTF-8"?>
<testsuites>
  ...
</testsuites>

[tclune]

Looks fine. Please rebase to the develop branch and add a comment in ChangeLog.md.

We'll probably be rolling out a new release of all the projects in this org in the next week or so (CMake min version issue). But let me know if you need a formal release sooner than that.

[melven]

Hi

thanks for your great work on pFUnit.

We are using it now in our own projects for more than 10 years now but we were still on some very outdated version before (3.3).

Our most important change is this here to make the xml output work in our CI.
(I will check the other changes but they are probably already fixed in the current version).

I rebased the changes onto the current develop branch.

[tclune]

@mathomp4 We will want to do a release of pFUnit with the other GFE projects.

[mathomp4]

@melven We'd like to get this in soon, could you add an entry to the changelog?

[melven]

Added changelog entry.
This probably leads to merge conflicts with other pull requests?

[mathomp4]

Added changelog entry. This probably leads to merge conflicts with other pull requests?

Thanks! We can fix any conflicts as needed.