chore(content): replace old-site message with open call submission promo

Signed-off-by: MissTipo <[email protected]>

Author: MissTipo

src/content/banner/en.mdx

@@ -1,8 +1,16 @@
 ---
 # Give each new message a unique title so we know which one a user closed
-title: "old-site"
-link: "https://archive.p5js.org"
+# title: "old-site"
+# link: "https://archive.p5js.org"
+# hidden: false
+# ---
+#
+# Looking for the old p5.js site? Find it here!
+
+# Open Call Promo
+title: "open-call"
+link: "https://openprocessing.org/curation/89576"
 hidden: false
 ---
 
-Looking for the old p5.js site? Find it here!
+We’re accepting p5.js sketches for a special curation exploring mental health and the newest features in p5.js 2.0! Submit by July 20!