CI: don't check for executable files in temp (MR 4858)

Most things in temp come from Alpine's aports repository, which has
different rules and does not for example mandate that files are not
marked as executable. As such, let's not require packages in there
to conform to our rules.

[ci:skip-build]: already built successfully in CI

.ci/testcases/test_directory_structure.py

@@ -30,7 +30,7 @@ def test_directories():
 # Ensure no file in pmaports are executable.
 # see https://gitlab.com/postmarketOS/pmaports/-/issues/593.
 def test_executable_files():
-    for file in glob.iglob("**/*", recursive=True):
+    for file in glob.iglob("[!temp]**/**/*", recursive=True):
         if os.path.isdir(file) or os.path.islink(file):
             continue
             # still check other less common inode types