Permit any printable ASCII character in files/

GLEP 33 says files/ entries should be within the ASCII range.
PMS does not make any further restrictions.

Exclude tilde (~) as this is commonly used by editors when saving backup
files.

One immediate benefit: this will allow for systemd template units to be
stored in files/ without mangling the filename. For example:

BannedCharacter: filename 'files/foo@.service' character outside allowed set: '@'

Signed-off-by: Mike Gilbert <floppym@gentoo.org>

src/pkgcheck/checks/pkgdir.py

@@ -19,6 +19,9 @@
 allowed_filename_chars.update(chr(x) for x in range(ord("0"), ord("9") + 1))
 allowed_filename_chars.update([".", "-", "_", "+", ":"])
 
+# allow any printable ascii character in FILESDIR
+allowed_filesdir_chars = set(chr(x) for x in range(33, 126))
+
 
 class MismatchedPN(results.PackageResult, results.Error):
     """Ebuilds that have different names than their parent directory."""
@@ -289,7 +292,7 @@ def feed(self, pkgset):
                             yield SizeViolation(
                                 pjoin(base_dir, filename), file_stat.st_size, pkg=pkg
                             )
-                    if banned_chars := set(filename) - allowed_filename_chars:
+                    if banned_chars := set(filename) - allowed_filesdir_chars:
                         yield BannedCharacter(
                             pjoin(base_dir, filename), sorted(banned_chars), pkg=pkg
                         )