Add Pkg.develop() back to Documenter.yml workflow

Since the docs are being built on Julia 1.10, they don't recognized the
`[sources]` section in Project.toml, so the package has to be `]dev`'d
in the docs workflow

Author: abhro

.github/workflows/Documenter.yml

@@ -22,7 +22,7 @@ jobs:
       - uses: julia-actions/cache@v2
       - name: Install dependencies
         shell: julia --color=yes --project=docs {0}
-        run: 'using Pkg; Pkg.instantiate()'
+        run: 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate()'
       - name: Build and deploy
         run: julia --color=yes --project=docs docs/make.jl
         env: