Update uvx run instructions to include Python version (3.13)

uvx ignores not only the lock file but also the Python
version specified in pyproject.toml.
https://github.com/astral-sh/uv/issues/8206#issuecomment-4113536371

docs/02-usage/040_workflow.md

@@ -29,7 +29,7 @@ To explicitly create a project, use the following command while in the project d
 
 For instance, when using `uvx`, run
 
-    uvx --from git+https://github.com/oraios/serena serena project create [options]
+    uvx -p 3.13 --from git+https://github.com/oraios/serena serena project create [options]
 
  * For an empty project, you will need to specify the programming language
    (e.g., `--language python`). 
@@ -201,7 +201,7 @@ Depending on the language backend being used, the management of resources for th
 
   where `<serena>` is your way of running Serena. For example, when using `uvx`, run
 
-      uvx --from git+https://github.com/oraios/serena serena start-project-server
+      uvx -p 3.13 --from git+https://github.com/oraios/serena serena start-project-server
 
 ### Multiple Agents Accessing a Single Serena Instance