Bump actions/download-artifact from 4 to 6 (#3329)

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v4...v6)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/compare-regdata.yml

@@ -205,7 +205,7 @@ jobs:
       DEPLOY_BRANCH: main
     steps:
       - name: Download all artifacts
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           path: comparison-artifacts
 

.github/workflows/post-release.yml

@@ -98,7 +98,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           path: /tmp
 

.github/workflows/pre-release.yml

@@ -62,7 +62,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@v6
         with:
           path: /tmp
 

.github/workflows/tardis-research-papers.yml

@@ -43,7 +43,7 @@ jobs:
       steps:
         - uses: actions/checkout@v5
 
-        - uses: actions/download-artifact@v5
+        - uses: actions/download-artifact@v6
           with:
             path: /tmp
 

.github/workflows/tests.yml

@@ -178,7 +178,7 @@ jobs:
           lockfile-path: ./conda-linux-64.lock
 
       # will download all artifacts(in this case all are coverage reports)
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           path: .
           merge-multiple: true