Update sponsors list

Author: jdavid

README.md

@@ -18,7 +18,7 @@ Supports Python 3.9 to 3.12 and PyPy3 7.3+
 
 ## Sponsors
 
--   [Iterative](https://iterative.ai/)
+- [Microsoft](https://github.com/microsoft)
 
 Add your name and link here, [become a
 sponsor](https://github.com/sponsors/jdavid).

SPONSORS.md

@@ -1,11 +1,13 @@
 Friends of pygit2:
 
-- [Iterative](https://iterative.ai/)
+- [Microsoft](https://github.com/microsoft)
 
 Add your name to the list,
 [become a friend of pygit2](https://github.com/sponsors/jdavid).
 
 Past sponsors:
 
+- [Iterative](https://iterative.ai/)
 - [SourceHut](https://sourcehut.org)
+- [GitHub](https://github.com/github)
 - [omniproc](https://github.com/omniproc)

docs/index.rst

@@ -19,7 +19,7 @@ Links
 Sponsors
 =====================================
 
-- `Iterative <https://iterative.ai/>`_
+- `Microsoft <https://github.com/microsoft>`_
 
 Add your name and link here, `become a sponsor <https://github.com/sponsors/jdavid>`_.