Update ACM MM conference data

- Fixed venue name for ACM MM 2025: "Royal Dublin Convention Centre" (corrected from "Dublin Royal Convention Center")
- Added missing author registration deadline for ACM MM 2026: August 20, 2026

These updates were verified through independent fact-checking of the official conference websites.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/data/conferences/acm_mm.yml

@@ -25,7 +25,7 @@
   date: October 27-31, 2025
   start: '2025-10-27'
   end: '2025-10-31'
-  venue: Dublin Royal Convention Center, Dublin, Ireland
+  venue: Royal Dublin Convention Centre, Dublin, Ireland
   note: All important dates can be found <a href='https://acmmm2025.org/important-dates/'>here</a>. The time for all dates is 23:59 AoE (Anywhere-on-Earth).
   tags:
   - computer-vision
@@ -62,6 +62,10 @@
       label: Camera-ready submission
       date: '2026-08-06 23:59:59'
       timezone: AoE
+    - type: registration
+      label: Author registration
+      date: '2026-08-20 23:59:59'
+      timezone: AoE
   city: Rio de Janeiro
   country: Brazil
   date: November 10-14, 2026
@@ -72,4 +76,4 @@
   - computer-vision
   - machine-learning
   - human-computer-interaction
-  era_rating: a
+  era_rating: a