Fix all GitHub Actions version tags

- Update julia-actions/julia-buildpkg from @1/@v1 to @v2
- Update julia-actions/julia-runtest from @1 to @v2
- Fixed in Downgrade.yml and Invalidations.yml

Author: ChrisRackauckas

.github/workflows/Downgrade.yml

@@ -28,8 +28,8 @@ jobs:
       - uses: julia-actions/julia-downgrade-compat@v2
         with:
           skip: Pkg,TOML
-      - uses: julia-actions/julia-buildpkg@1
-      - uses: julia-actions/julia-runtest@1
+      - uses: julia-actions/julia-buildpkg@v2
+      - uses: julia-actions/julia-runtest@v2
         with:
           ALLOW_RERESOLVE: false
         env:

.github/workflows/Invalidations.yml

@@ -20,14 +20,14 @@ jobs:
       with:
         version: '1'
     - uses: actions/checkout@v4
-    - uses: julia-actions/julia-buildpkg@v1
+    - uses: julia-actions/julia-buildpkg@v2
     - uses: julia-actions/julia-invalidations@v1
       id: invs_pr
 
     - uses: actions/checkout@v4
       with:
         ref: ${{ github.event.repository.default_branch }}
-    - uses: julia-actions/julia-buildpkg@v1
+    - uses: julia-actions/julia-buildpkg@v2
     - uses: julia-actions/julia-invalidations@v1
       id: invs_default