Update python version in brew command (#17593)

* Update python version in brew command

Previously brew command installed python version 2 (outdated). Now brew command will install python 3.

* Create 17590.md

* Rewording news file description

Co-authored-by: Karthik Nadig <[email protected]>

Co-authored-by: Karthik Nadig <[email protected]>

Author: Carolinekung2

news/1 Enhancements/17590.md

@@ -0,0 +1,2 @@
+Update homebrew instructions to install python 3.
+(thanks [Carolinekung2 ](https://github.com/Carolinekung2))

resources/walkthrough/install-python-macos.md

@@ -3,7 +3,7 @@
 If you have [Homebrew](https://brew.sh/) installed, you can install Python by running the following command in the terminal (<kbd>Ctrl</kbd> + <kbd>Shift</kbd> + <kbd>`</kbd>):
 
 ```
-brew install python
+brew install python3
 ```
 
 If you don't have Homebrew, you can download a Python installer for macOS from [python.org](https://www.python.org/downloads/mac-osx/).