Pin GHA to Ubuntu 18.04
`ubuntu-latest` points to 18.04 and will soon flip to 20.04.
However tests currently fail on 20.04, so let's explicitly pin to 18.04 for now.
@@ -10,7 +10,7 @@ jobs:
fail-fast: false
matrix:
python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9]
- os: [ubuntu-latest, macOS-latest, windows-latest]
+ os: [ubuntu-18.04, macOS-latest, windows-latest]
include:
# pypy3 on Mac OS currently fails trying to compile
# brotlipy. Moving pypy3 to only test linux.
