chore: Update Alvaro Serra's left date and add postdoc information

_people/alvaro-serra.md

@@ -3,7 +3,7 @@ name: Álvaro Serra Gómez
 title: PhD Candidate # The title that shows below your name.
 type: phd-candidate # phd-candidate, post-doc, phd-visitor, professor, engineer. These are used for filtering and grouping people.
 joined_date: 2019-07-01
-# left_date: 2023-09-30 # Optional, if you add a left date the member will be moved to the past members section
+left_date: 2024-05-01 # Optional, if you add a left date the member will be moved to the past members section
 # now_at: Assistant Professor at Cool Uni # Add this for extra info for past members
 image: /assets/images/people/SerraGómez_Alvaro.jpg # link or path in /assets/...
 links: # Optional, links to other stuff
@@ -14,4 +14,5 @@ links: # Optional, links to other stuff
 ---
 
 <!-- Here add your interests or small paragraph. Keep it brief -->
-Motion planning for multi-robot high-level scene reasoning
+Motion planning for multi-robot high-level scene reasoning. Now Postdoc at Leiden University. 
+```