Update ci

Author: zjwegert

.github/workflows/ci.yml

@@ -50,7 +50,8 @@ jobs:
           julia --project=docs -e '
             using Pkg
             Pkg.develop(PackageSpec(path=pwd()))
-            Pkg.instantiate()'
+            Pkg.instantiate()
+            Pkg.add(name="GridapSolvers", rev="develop")'
       - run: julia --project=docs docs/make.jl
         env:
           DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}