fix(ci): Use unique name for artifacts (#3091)

Fixes
https://github.com/firezone/firezone/actions/runs/7390085822/job/20104967154

See
https://github.com/actions/upload-artifact/blob/main/docs/MIGRATION.md

.github/workflows/_elixir.yml

@@ -505,7 +505,7 @@ jobs:
           && always() }}
         uses: actions/upload-artifact@v4
         with:
-          name: screenshots
+          name: screenshots-${{ matrix.MIX_TEST_PARTITION }}
           path: elixir/apps/web/screenshots
       - name: Test Report
         uses: dorny/test-reporter@v1

.github/workflows/cd.yml

@@ -228,7 +228,7 @@ jobs:
       - name: Upload digest
         uses: actions/upload-artifact@v4
         with:
-          name: digests
+          name: ${{ matrix.name.artifact }}-digest
           path: /tmp/digests/*
           if-no-files-found: error
           retention-days: 1