upgrade github actions

[awalterschulze]

This should get rid of some warnings in CI, so that the table is closer to the top of the results

In ci.yml, simply update the following versions:

- uses: jaxxstorm/action-install-gh-release@v2.1.0
+ uses: jaxxstorm/action-install-gh-release@v3.0.0

- uses: actions/checkout@v4
+ uses: actions/checkout@v6

- uses: actions/cache/restore@v4
+ uses: actions/cache/restore@v5

- uses: actions/upload-artifact@v4
+ uses: actions/upload-artifact@v7

uses: actions/download-artifact@v4
uses: actions/download-artifact@v8

Other new versions include
uses: actions/cache/save@v5