doc: update version requirement. closes #9372 (#9387)

Author: sappelhoff

doc/install/contributing.rst

@@ -174,7 +174,7 @@ Creating the virtual environment
 These instructions will set up a Python environment that is separated from your
 system-level Python and any other managed Python environments on your computer.
 This lets you switch between different versions of Python (MNE-Python requires
-version 3.6 or higher) and also switch between the stable and development
+version 3.7 or higher) and also switch between the stable and development
 versions of MNE-Python (so you can, for example, use the same computer to
 analyze your data with the stable release, and also work with the latest
 development version to fix bugs or add new features). Even if you've already

doc/install/index.rst

@@ -1,7 +1,7 @@
 Quick start
 ===========
 
-MNE-Python requires Python version 3.6 or higher.
+MNE-Python requires Python version 3.7 or higher.
 For users already familiar with Python:
 
 - If you only need 2D plotting capabilities with MNE-Python (i.e., most EEG/ERP

doc/install/mne_python.rst

@@ -13,7 +13,7 @@ Installing Python
 ^^^^^^^^^^^^^^^^^
 
 MNE-Python runs within Python, and depends on several other Python packages.
-Starting with version 0.21, MNE-Python only supports Python version 3.6 or
+Starting with version 0.24, MNE-Python only supports Python version 3.7 or
 higher. We strongly
 recommend the `Anaconda`_ distribution of Python, which comes with more than
 250 scientific packages pre-bundled, and includes the ``conda`` command line
@@ -37,8 +37,8 @@ you should see outputs similar to the following (assuming you installed
 conda to ``/home/user/anaconda3``)::
 
     $ conda --version && python --version
-    conda 4.6.2
-    Python 3.6.7 :: Anaconda, Inc.
+    conda 4.9.2
+    Python 3.7.7 :: Anaconda, Inc.
     $ which python
     /home/user/anaconda3/bin/python
     $ which pip