[pygobject/pyproject-toml-v2] Revert "Revert "Add PEP518/pyproject.toml file""

[Christoph Reiter <creiter src gnome org>]

commit fe33c56b60ae88ea3ad1632ef8193176a9b1906f
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Tue Nov 13 21:32:50 2018 +0100

    Revert "Revert "Add PEP518/pyproject.toml file""
    
    This was reverted because pip didn't support installing build deps
    from sdists. But this looks fixed since https://github.com/pypa/pip/pull/5336
    
    pip now builds and installs pycairo before building pygobject.
    
    This reverts commit ad1bbfa148b7734e2fca3c9f0e14ddab630bc354.

 MANIFEST.in    | 1 +
 pyproject.toml | 2 ++
 2 files changed, 3 insertions(+)
---
diff --git a/MANIFEST.in b/MANIFEST.in
index 25de999e..72cb04c2 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,4 +1,5 @@
 include setup.cfg
+include pyproject.toml
 include COPYING
 include *.in
 include NEWS
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 00000000..830e77af
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,2 @@
+[build-system]
+requires = ["setuptools", "wheel", "pycairo"]