CI: tests on lts an release versions, build doc on release

Author: franckgaga

.github/workflows/CI.yml

@@ -19,8 +19,8 @@ jobs:
       fail-fast: false
       matrix:
         version:
-          - '1.6'
-          - '1'
+          - 'release'
+          - 'lts'
           - 'nightly'
         os:
           - ubuntu-latest

.github/workflows/documentation.yml

@@ -16,7 +16,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: julia-actions/setup-julia@v1
         with:
-          version: '1'
+          version: 'release'
       - name: Install dependencies
         run: julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate()'
       - name: Build and deploy