Python dependency upgraded to version 3

node-gyp officially requires Python 3

Author: ferenczy

docs/contributing/setup-linux.md

@@ -4,7 +4,7 @@ You will need to install these tools on your machine:
 
  - Node.js
  - Yarn
- - Python 2
+ - Python 3
  - Electron dependencies
 
 ## Node.js
@@ -32,10 +32,10 @@ If you're not familiar with `yarn`, please read [this document](./working-with-p
 to help familiarize yourself with how to do the common package tasks that are
 relevant to Desktop.
 
-## Python 2
+## Python 3
 
 Refer to your distributions package manager to obtain the latest version of the
-Python 2 series.
+Python 3 series.
 
 ## Electron dependencies
 

docs/contributing/setup-macos.md

@@ -4,7 +4,7 @@ You will need to install these tools on your machine:
 
  - Node.js
  - Yarn
- - Python 2
+ - Python 3
  - Xcode and Xcode Command Line Tools (Xcode -> Preferences -> Downloads)
 
 ## Node.js
@@ -70,10 +70,10 @@ relevant to Desktop.
 macOS comes with Python pre-installed, and it happens to be the right version, so you're probably fine! But let's be sure. Open a terminal and run this command inside the Desktop source directory:
 
 ```shellsession
-$ python --version
+$ python3 --version
 ```
 
-If you see the output `Python 2.7.x`, you're good to go!
+If you see the output `Python 3.9.x`, you're good to go!
 
 ### I need to use different versions of Python in different projects!
 
@@ -87,13 +87,13 @@ For this, we recommend [pyenv](https://github.com/pyenv/pyenv). (It's the only g
 pyenv install
 ```
 
-3. Verify you have the right version by running `python --version` again:
+3. Verify you have the right version by running `python3 --version` again:
 
 ```shellsession
-$ python --version
+$ python3 --version
 ```
 
-If you see the output `Python 2.7.x`, you're good to go!
+If you see the output `Python 3.9.x`, you're good to go!
 
 ## Xcode Command Line Tools
 

docs/contributing/setup-windows.md

@@ -4,7 +4,7 @@ You will need to install these tools on your machine:
 
  - Node.js
  - Yarn
- - Python 2
+ - Python 3
  - Visual C++ Build Tools
 
 ## Node.js
@@ -74,16 +74,19 @@ Open a shell and run this command:
 $ python --version
 ```
 
-If you see the output `Python 2.7.x`, you're good to go!
+If you see the output `Python 3.9.x`, you're good to go!
 
 If you see an error about being unable to find `python`, that probably means you
-don't have Python installed. You can install Python 2.7 from the
+don't have Python installed. You can install Python 3.9 from the
 [Python website](https://www.python.org/downloads/windows/).
 
 **Python installation notes:**
 
- - Let Python install into the default suggested path (`c:\Python27`), otherwise
+ - Let Python install into the default suggested path (`c:\Python39`), otherwise
    you'll have to configure `node-gyp` manually to look at a different path.
+ - In the case you already have or need to have Python on a different path, set the `PYTHON` environment variable or the npm's `python` config key to your Python's executable path:
+
+         npm config set python "c:\path\to\python3\python.exe"
  - Ensure the **Add python.exe to Path** option is selected.
 
 ## Visual C++ Build Tools