Bump to ubuntu-20.04

Author: ericmj

.github/workflows/main.yml

@@ -5,7 +5,7 @@ on: [push, pull_request]
 jobs:
   format:
     name: Format
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v3
 
@@ -24,7 +24,7 @@ jobs:
 
   test:
     name: Test
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
 
     services:
       postgres:
@@ -87,7 +87,7 @@ jobs:
 
       - name: Install OTP and Elixir for hexpm
         run: |
-          wget https://builds.hex.pm/builds/otp/ubuntu-18.04/${HEXPM_OTP}.tar.gz
+          wget https://builds.hex.pm/builds/otp/ubuntu-20.04/${HEXPM_OTP}.tar.gz
           mkdir -p ${HEXPM_OTP_PATH}
           tar -xf ${HEXPM_OTP}.tar.gz -C ${HEXPM_OTP_PATH} --strip-components=1
           ${HEXPM_OTP_PATH}/Install -minimal $(pwd)/${HEXPM_OTP_PATH}