ci: fix Pkg import

Author: MilesCranmer

.github/workflows/fix-format.yml

@@ -11,7 +11,7 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install JuliaFormatter and format
         run: |
-          julia  -e 'import Pkg; Pkg.add(PackageSpec(name="JuliaFormatter", version="1"))'
+          julia  -e 'import Pkg; Pkg.add(Pkg.PackageSpec(name="JuliaFormatter", version="1"))'
           julia  -e 'using JuliaFormatter; format(".")'
 
       - name: Create Pull Request