Bump leafo/gh-actions-luarocks from v3 to v4 (Mudlet#4378)

Bumps [leafo/gh-actions-luarocks](https://github.com/leafo/gh-actions-luarocks) from v3 to v4.
- [Release notes](https://github.com/leafo/gh-actions-luarocks/releases)
- [Commits](leafo/gh-actions-luarocks@v3...218573c)

Signed-off-by: dependabot[bot] <support@github.com>

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

.github/workflows/update-autocompletion.yml

@@ -16,7 +16,7 @@ jobs:
       with:
         luaVersion: "5.1.5"
     - uses: actions/setup-node@v2.1.2
-    - uses: leafo/gh-actions-luarocks@v3
+    - uses: leafo/gh-actions-luarocks@v4
 
     - name: install Lua dependencies
       run: |

.github/workflows/update-geyser-docs.yml

@@ -19,7 +19,7 @@ jobs:
       with:
         luaVersion: "5.1.5"
 
-    - uses: leafo/gh-actions-luarocks@v3
+    - uses: leafo/gh-actions-luarocks@v4
       name: Install LuaRocks
 
     - name: Install LDoc