Add Paris 2021 as upcoming event

Fixes #5

Author: fbiville

_data/events.yml

@@ -1,8 +1,11 @@
-upcoming: []
+upcoming:
+  - name: Paris 2021
+    url: https://paris2021.hack-commit-pu.sh/
+    img: hcp-paris-2021.png
 past:
   - name: Paris 2020
     url: https://paris2020.hack-commit-pu.sh/
     img: hcp-paris-2020.png
   - name: Paris 2019
     url: https://paris2019.hack-commit-pu.sh/
-    img: hcp-paris-2019.png
+    img: hcp-paris-2019.png