Repository: fatiando/boule (language: python)

Issue:
Drop support for Python 3.6
<!-- Please describe your suggestion/problem/question in as much detail as possible. -->
Now that v0.4.0 is out, we can drop support for Python 3.6. To do so:

1. Remove it from `setup.cfg` descriptors
2. Bump the minimum version in `setup.cfg`
3. Bump the minimum version in the test GitHub actions workflow
4. Update the Install instructions in the documentation


Discussion / hints:

Fix patch:
diff --git a/doc/install.rst b/doc/install.rst
index 694be960..226025bc 100644
--- a/doc/install.rst
+++ b/doc/install.rst
@@ -42,7 +42,7 @@ There are different ways to install Boule:
 Which Python?
 -------------
 
-You'll need **Python >= 3.6**.
+You'll need **Python >= 3.7**.
 See :ref:`python-versions` if you require support for older versions.
 
 Dependencies
diff --git a/setup.cfg b/setup.cfg
index a06bec02..4f73873a 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -23,7 +23,6 @@ classifiers =
     Topic :: Scientific/Engineering
     Topic :: Software Development :: Libraries
     Programming Language :: Python :: 3 :: Only
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
@@ -38,7 +37,7 @@ project_urls =
 [options]
 zip_safe = True
 packages = find:
-python_requires = >=3.6
+python_requires = >=3.7
 install_requires =
     numpy>=1.19
     attrs>=19.3.0


Test patch:
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 6e0aae9f..dd8abd56 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -39,9 +39,9 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu, macos, windows]
-        python: ["3.6", "3.10"]
+        python: ["3.7", "3.10"]
         include:
-          - python: "3.6"
+          - python: "3.7"
             dependencies: oldest
           - python: "3.10"
             dependencies: latest