docs: Update docs for v4.9 release (#6707)

Co-authored-by: Wojciech Tyczyński <tykus160@gmail.com>

maintained-branches.md

@@ -2,8 +2,8 @@
 
 We are currently maintaining the following branches of Shaka Player:
 
- - v4.8 (latest)
- - v4.7 (previous)
+ - v4.9 (latest)
+ - v4.8 (previous)
  - v4.3 (in use by the Cast Application Framework)
  - No active LTS branches at this time
 

roadmap.md

@@ -20,16 +20,22 @@ Candidate features for future release cycles:
 v5.0 - 2024 Q4
  - Conversion to Typescript
 
-v4.9 - 2024 Q3
+v4.10 - 2024 Q3
+ - HLS support for EXT-X-DATERANGE
+   https://github.com/shaka-project/shaka-player/issues/3523
+ - HLS interstitials
+   https://github.com/shaka-project/shaka-player/issues/3364
+
+=====
+
+v4.9 - 2024 Q2
  - DASH patch manifests
    https://github.com/shaka-project/shaka-player/issues/2228
  - DASH: MPD chaining
    https://github.com/shaka-project/shaka-player/issues/3926
  - Support CS on devices that don't support multiple media elements
    https://github.com/shaka-project/shaka-player/issues/2792
 
-=====
-
 v4.8 - 2024 Q2
  - Preload API
    https://github.com/shaka-project/shaka-player/issues/880