fix(cache): switch to filesystem backend for CachedSession to resolve locking issues

Fix the "sqlite: bad parameter or other api misuse" error reported on Ubuntu, Windows, and Android by changing the requests_cache backend from sqlite to filesystem.

This uses a directory-based cache instead of a single file, eliminating locking problems in concurrent environments.

No breaking changes; cache behavior remains compatible.

Fixes: #10, #11

Author: smithemely

tstickers/caching.py

@@ -11,8 +11,8 @@
 
 # requests_cache
 cachedSession = CachedSession(
-	".cache/tstickers.requests.sqlite",
-	backend="sqlite",
+	".cache/tstickers.requests",
+	backend="filesystem",
 	expire_after=60 * 60 * 12,
 	allowable_codes=(200,),
 	allowable_methods=("GET", "POST"),