Drop Python 3.6 support (#434)

.github/workflows/python-package.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.6.9, 3.7, 3.8, 3.9]
+        python-version: [3.7, 3.8, 3.9]
 
     steps:
     - uses: actions/checkout@v2

.github/workflows/update-site-data.yml

@@ -2,7 +2,7 @@ name: Update sites rating and statistics
 
 on:
   pull_request:
-    branches: [ main ]
+    branches: [ dev ]
     types: [opened, synchronize]
 
 jobs:

README.md

@@ -51,7 +51,7 @@ Also you can run Maigret using cloud shells and Jupyter notebooks (see buttons b
 
 ### Package installing
 
-**NOTE**: Python 3.6 or higher and pip is required, **Python 3.8 is recommended.**
+**NOTE**: Python 3.7 or higher and pip is required, **Python 3.8 is recommended.**
 
 ```bash
 # install from pypi