ci: drop support for Python 3.6, test again Python 3.10

Author: darosior

.github/workflows/python-package.yml

@@ -10,7 +10,7 @@ jobs:
   tests:
     strategy:
       matrix:
-        python-version: [3.6, 3.7, 3.8, 3.9]
+        python-version: [3.7, 3.8, 3.9, 3.10]
         os:
           - ubuntu-latest
           - macOS-latest

CHANGELOG.md

@@ -1,3 +1,10 @@
+# Unreleased
+
+This is a breaking release.
+
+- Python 3.10 support.
+- Drop Python 3.6 support (EOL).
+
 # 2.1
 
 - Two new methods were added: `get_xpub_bytes()` and `get_xpriv_bytes()`