update CI workflows to use Ubuntu 20.04 (since Ubuntu 18.04 is deprec…

…ated)

.github/workflows/bootstrap_script.yml

@@ -3,7 +3,7 @@ name: test EasyBuild bootstrap script
 on: [push, pull_request]
 jobs:
   setup:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     outputs:
         lmod7: Lmod-7.8.22
         lmod8: Lmod-8.7.6
@@ -14,7 +14,7 @@ jobs:
       - run: "true"
   build:
     needs: setup
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         # Don't run for Python 3.8, 3.9 , people should just use `pip install easybuild`

.github/workflows/container_tests.yml

@@ -4,7 +4,7 @@ on: [push, pull_request]
 jobs:
   build:
     # stick to Ubuntu 18.04, where we can still easily install yum via 'apt-get install'
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python: [2.7, 3.6]

.github/workflows/eb_command.yml

@@ -3,7 +3,7 @@ name: Tests for the 'eb' command
 on: [push, pull_request]
 jobs:
   test-eb:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9, '3.10']

.github/workflows/linting.yml

@@ -2,7 +2,7 @@ name: Static Analysis
 on: [push, pull_request]
 jobs:
   python-linting:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9, '3.10']

.github/workflows/unit_tests.yml

@@ -3,7 +3,7 @@ name: EasyBuild framework unit tests
 on: [push, pull_request]
 jobs:
   setup:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     outputs:
         lmod7: Lmod-7.8.22
         lmod8: Lmod-8.7.6
@@ -14,7 +14,7 @@ jobs:
       - run: "true"
   build:
     needs: setup
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python: [2.7, 3.6]