Set the default Python version to 3.13 in the uv installation guide (#4480)

* Set the default python version to 3.13 in the uv installation guide.

* Capitalize Python

---------

Co-authored-by: Francisco Manríquez Novoa <49853152+chopan050@users.noreply.github.com>

Author: henrikmidtiby

docs/source/installation/uv.md

@@ -153,8 +153,10 @@ The following commands will
 The name for the Python project is *manimations*, which you can change
 to anything you like.
 
+Manim does not yet support Python 3.14 and the Python version is therefore set to 3.13.
+
 ```bash
-uv init manimations
+uv init --python 3.13 manimations
 cd manimations
 uv add manim
 ```
@@ -200,8 +202,10 @@ Manim itself! The following commands will
 The name for the Python project is *manimations*, which you can change
 to anything you like.
 
+Manim does not yet support Python 3.14 and the Python version is therefore set to 3.13.
+
 ```bash
-uv init manimations
+uv init --python 3.13 manimations
 cd manimations
 uv add manim
 ```
@@ -253,11 +257,13 @@ As soon as the required dependencies are installed, you can create
 a Python project (feel free to change the name *manimations* used below
 to some other name) with a local environment containing Manim by running
 ```bash
-uv init manimations
+uv init --python 3.13 manimations
 cd manimations
 uv add manim
 ```
 
+Manim does not yet support Python 3.14 and the Python version is therefore set to 3.13.
+
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