Add sponsorship details for GitHub Sponsor button (GH-14181)



diff --git a/.github/FUNDING.yml b/.github/FUNDING.yml
new file mode 100644
index 0000000..36c4e27
--- /dev/null
+++ b/.github/FUNDING.yml
@@ -0,0 +1 @@
+custom: https://www.python.org/psf/donations/python-dev/