Update README.md

Co-authored-by: Andrew Murray <3112309+radarhere@users.noreply.github.com>

Author: aclark4life

README.md

@@ -10,7 +10,7 @@ Pillow is the friendly PIL fork by [Jeffrey 'Alex' Clark and
 contributors](https://github.com/python-pillow/Pillow/graphs/contributors).
 PIL is the Python Imaging Library by Fredrik Lundh and contributors.
 Development is supported by:
-- [Tidelift](https://tidelift.com/subscription/pkg/pypi-pillow?utm_source=pypi-pillow&utm_medium=readme&utm_campaign=enterprise) (since 2019)
+- [Tidelift](https://tidelift.com/subscription/pkg/pypi-pillow?utm_source=pypi-pillow&utm_medium=readme&utm_campaign=enterprise) (since 2018)
 - [Thanks.dev](https://thanks.dev) (since 2023)
 - [GitHub Sponsors](https://github.com/sponsors/python-pillow) (since 2026)