Fix HTML syntax in sponsorship section of README

Author: goruha

README.yaml

@@ -12,9 +12,9 @@ description: |-
   ## Sponsorship
 
   <picture>
-    <source media="(prefers-color-scheme: dark)" srcset="https://cloudposse.com/images/partners/datadog-white.svg">
-    <source media="(prefers-color-scheme: light)" srcset="https://cloudposse.com/images/partners/datadog-purple.svg">
-    <img alt="Datadog" src="https://cloudposse.com/images/partners/datadog-purple.svg" align="right" width="40%">
+    <source media="(prefers-color-scheme: dark)" srcset="https://cloudposse.com/images/partners/datadog-white.svg"/>
+    <source media="(prefers-color-scheme: light)" srcset="https://cloudposse.com/images/partners/datadog-purple.svg"/>
+    <img alt="Datadog" src="https://cloudposse.com/images/partners/datadog-purple.svg" align="right" width="40%"/>
   </picture>