ci: pin juliaformatter to 2.4.0 in format workflows (#614)

Author: MilesCranmer

.github/workflows/check-format.yml

@@ -25,7 +25,7 @@ jobs:
         uses: julia-actions/cache@v3
       - name: Install JuliaFormatter and format
         run: |
-          julia --startup-file=no -e 'using Pkg; pkg"activate --temp"; pkg"add JuliaFormatter@2"; using JuliaFormatter; format("."; verbose=true)'
+          julia --startup-file=no -e 'using Pkg; pkg"activate --temp"; pkg"add JuliaFormatter@2.4.0"; using JuliaFormatter; format("."; verbose=true)'
       - name: "Format check"
         run: |
           julia -e '

.github/workflows/fix-format.yml

@@ -20,7 +20,7 @@ jobs:
         uses: julia-actions/cache@v3
       - name: "Install JuliaFormatter and format"
         run: |
-          julia  -e 'using Pkg; pkg"add JuliaFormatter@1.0.61"'
+          julia  -e 'using Pkg; pkg"add JuliaFormatter@2.4.0"'
           julia  -e 'using JuliaFormatter; format(".")'
       - name: "Create Pull Request"
         id: cpr