📌 Track submodule pymc-examples to main branch

* Configure .gitmodules to specify branch for submodule
* closes #4357

Author: CloudChaoszero

.gitmodules

@@ -1,4 +1,4 @@
 [submodule "docs/source/pymc-examples"]
 	path = docs/source/pymc-examples
-	url = git@github.com:pymc-devs/pymc-examples.git
+	url = https://github.com/pymc-devs/pymc-examples.git
         branch = main