cache: More aggressive default

src/cache.c

@@ -18,7 +18,7 @@
 GIT__USE_OIDMAP
 
 bool git_cache__enabled = true;
-int64_t git_cache__max_storage = (4 * 1024 * 1024);
+int64_t git_cache__max_storage = (256 * 1024 * 1024);
 
 static git_atomic64 git_cache__current_storage = {0};