Please v11.0.0 released

[Peter Ebden]

The new version is done, and due to a few small breaking changes it's a major version.

The headline feature this time is a complete builtin parser engine so it's independent of OS-level Python and no longer has any requirement to install Python, PyPy or cffi.

Shortly behind that is an option for interactive test debugging; passing -d to plz test or plz cover now allows it to break into an interactive debugger on test failure. This only works on one test at a time and currently only for Python (using pytest), C and C++ (where it breaks into gdb on faults).

See https://github.com/thought-machine/please/releases/tag/v11.0.0 for more details & downloads etc.

Thanks to everyone who contributed, made suggestions & reviewed changes!

-P