Update CI configuration to Julia 1.6, enable nightly for Linux.

Author: fredrikekre

.github/workflows/Documenter.yml

@@ -14,7 +14,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: julia-actions/setup-julia@latest
         with:
-          version: '1.5'
+          version: '1.6'
       - name: Install dependencies
         run: julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate()'
       - name: Build and deploy

.github/workflows/ci.yml

@@ -18,15 +18,18 @@ jobs:
       fail-fast: false
       matrix:
         version:
+          - '1.6'
           - '1'
-          - '1.3'
-          # - 'nightly'
         os:
           - ubuntu-latest
           - macOS-latest
           - windows-latest
         arch:
           - x64
+        include:
+          - os: ubuntu-latest
+            version: 'nightly'
+            arch: x64
     steps:
       - uses: actions/checkout@v2
       - uses: julia-actions/setup-julia@v1