Missing link to libpython3.8 when using Python 3.8
See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=951779 for details.
Summary is
/usr/bin/ld: renderer@sha/pitivi_coptimizations_renderer.c.o: in function `py_fill_surface':
./deb-build/../pitivi/coptimizations/renderer.c:30: undefined reference to `PyList_Type'
/usr/bin/ld: ./deb-build/../pitivi/coptimizations/renderer.c:30: undefined reference to `PyArg_ParseTuple'
/usr/bin/ld: ./deb-build/../pitivi/coptimizations/renderer.c:33: undefined reference to `PyList_Size'
/usr/bin/ld: ./deb-build/../pitivi/coptimizations/renderer.c:50: undefined reference to `PyList_GetItem'
/usr/bin/ld: ./deb-build/../pitivi/coptimizations/renderer.c:51: undefined reference to `PyFloat_AsDouble'
/usr/bin/ld: ./deb-build/../pitivi/coptimizations/renderer.c:54: undefined reference to `PyErr_Occurred'
Probably same as https://gitlab.freedesktop.org/gstreamer/gst-python/-/merge_requests/29