chore: simplify tests workflow

Taking advantage of the Emacs images available on my runner

.gitea/workflows/test.yml

@@ -3,43 +3,16 @@ on: [push, pull_request]
 
 jobs:
   build:
-    runs-on: ubuntu-latest
     strategy:
       matrix:
         emacs_version:
-          - 26.3
-          - 27.2
-          - 28.2
-          - 29.1
-          - snapshot
+          - emacs-26-alpine-ci-eask
+          - emacs-27-alpine-ci-eask
+          - emacs-28-alpine-ci-eask
+          - emacs-29-alpine-ci-eask
+          - emacs-master-alpine-ci-eask
+    runs-on: ${{ matrix.emacs_version }}
     steps:
       - uses: actions/checkout@v3
-
-      - uses: actions/cache@v3
-        id: cache-nix-conf
-        with:
-          path: /etc/nix
-          key: cache-nix-conf-000
-
-      - uses: actions/cache@v3
-        id: cache-nix-packages
-        with:
-          path: /nix
-          key: cache-nix-packages-000
-
-      - uses: purcell/setup-emacs@master
-        with:
-          version: ${{ matrix.emacs_version }}
-
-      - uses: actions/cache@v3
-        id: cache-eask-packages
-        with:
-          path: .eask
-          key: cache-eask-packages-000
-
-      - uses: emacs-eask/setup-eask@master
-        with:
-          version: 'snapshot'
-
       - name: "Execute Eask CI"
         run: make ci