Update http3 for Safari support (#2436)

Author: jamesnw

features/http3.yml

@@ -6,10 +6,13 @@ caniuse: http3
 # from https://caniuse.com/http3. TODO: capture partial support in Safari with
 # notes. caniuse says "Enabled by default for a portion of users."
 status:
-  baseline: false
+  baseline: low
+  baseline_low_date: 2024-09-16
   support:
     chrome: "87"
     chrome_android: "87"
     edge: "87"
     firefox: "88"
     firefox_android: "88"
+    safari: "18"
+    safari_ios: "18"