build(linux): fix new lint errors (#2953)

packaging/linux/flatpak/flatpak-lint-baseline_repo.json

@@ -1,10 +1,10 @@
 {
     "errors": [
-        "appstream-external-screenshot-url",
+        "appstream-missing-screenshots",
         "finish-args-flatpak-spawn-access"
     ],
     "info": [
-        "appstream-external-screenshot-url: Screenshots are not mirrored to https://dl.flathub.org/media",
+        "appstream-missing-screenshots: Catalogue file has no screenshots. Please check if screenshot URLs are reachable",
         "finish-args-flatpak-spawn-access: finish-args has a talk-name access for org.freedesktop.Flatpak"
     ],
     "message": "Please consult the documentation at https://docs.flathub.org/docs/for-app-authors/linter"

packaging/sunshine.rb

@@ -145,10 +145,10 @@ class @PROJECT_NAME@ < Formula
 
   test do
     # test that the binary runs at all
-    system "#{bin}/sunshine", "--version"
+    system bin/"sunshine", "--version"
 
     # run the test suite
     # cannot build tests with python tests because homebrew destroys the source directory
-    system "#{bin}/test_sunshine", "--gtest_color=yes"
+    system bin/"test_sunshine", "--gtest_color=yes"
   end
 end