Merge pull request #246 from lektor/upgrade-py-node-build-versions

Downgrading to 3.6 in the travis docs. 3.7 doesn't work there without sudo / xenial.

content/docs/deployment/travisci/contents.lr

@@ -24,7 +24,7 @@ file into your repository.  You can copy paste this over:
 
 ```yaml
 language: python
-python: 3.7
+python: 3.6
 install: "pip install Lektor"
 script: "lektor build"
 deploy:
@@ -115,7 +115,7 @@ caching.  Adjust your `.travis.yml` file to look like this:
 
 ```yaml
 language: python
-python: 3.7
+python: 3.6
 cache:
   directories:
     - $HOME/.cache/pip
@@ -135,7 +135,7 @@ config:
 
 ```yaml
 language: python
-python: 3.7
+python: 3.6
 cache:
   directories:
     - $HOME/.cache/pip