drop python 3.7

Signed-off-by: Nathaniel Starkman (@nstarman) <nstarkman@protonmail.com>

.github/workflows/ci_cron.yml

@@ -40,14 +40,14 @@ jobs:
           # that gives too many false positives due to URL timeouts. We also
           # install all dependencies via pip here so we pick up the latest
           # releases.
-          - name: Python 3.7 with dev version of key dependencies
+          - name: Python 3.8 with dev version of key dependencies
             os: ubuntu-latest
-            python: 3.7
+            python: 3.8
             toxenv: py37-test-devdeps
 
           - name: Documentation link check
             os: ubuntu-latest
-            python: 3.7
+            python: 3.8
             toxenv: linkcheck
 
           - name: Bundling with pyinstaller

.github/workflows/ci_tests.yml

@@ -129,14 +129,14 @@ jobs:
           # NOTE: In the build below we also check that tests do not open and
           # leave open any files. This has a performance impact on running the
           # tests, hence why it is not enabled by default.
-          - name: py3.7 - oldest deps
+          - name: py3.8 - oldest deps
             os: ubuntu-16.04
-            python: 3.7
+            python: 3.8
             toxenv: py37-test-oldestdeps
 
-          - name: py3.7 - all deps, numpy 1.17 | coverage
+          - name: py3.8 - all deps, numpy 1.17 | coverage
             os: ubuntu-latest
-            python: 3.7
+            python: 3.8
             toxenv: py37-test-alldeps-numpy117-cov-clocale
             # toxposargs: --remote-data=discO
 
@@ -187,7 +187,7 @@ jobs:
 
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python: [3.7, 3.8]
+        python: [3.8, 3.9]
 
     steps:
     - uses: actions/checkout@v2

setup.cfg

@@ -14,7 +14,7 @@ github_project = nstarman/discO
 [options]
 zip_safe = False
 packages = find:
-python_requires = >=3.7
+python_requires = >=3.8
 setup_requires = setuptools_scm
 install_requires =
     astropy