Fix alignment guessing algorithm returning invalid values

If the GCD is not a power of 2, that means the files in the archive
are most likely not aligned (since files are always aligned to
2**n byte boundaries).

sarc/sarc.py

@@ -61,6 +61,11 @@ def guess_default_alignment(self) -> int:
         gcd = next(iter(self._files.values()))[0] + self._doff
         for node in self._files.values():
             gcd = math.gcd(gcd, node[0] + self._doff)
+
+        if gcd == 0 or gcd & (gcd - 1) != 0:
+            # If the GCD is not a power of 2, the files are mostly likely NOT aligned.
+            return 4
+
         return gcd
 
     def get_data_offset(self) -> int:

setup.py

@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name="sarc",
-    version="1.0.0-1",
+    version="1.0.1",
     author="leoetlino",
     author_email="leo@leolam.fr",
     description="Nintendo SARC archive reader and writer",