implement automatic updater

updater/certificates.py

@@ -0,0 +1,11 @@
+import subprocess
+
+
+def get_apk_certificate(file: str):
+    output = subprocess.check_output(['keytool', '-printcert', '-rfc', '-jarfile', file], text=True)
+    lines = output.split("\n")
+    return '\n'.join(lines[
+        lines.index('-----BEGIN CERTIFICATE-----'):
+        (lines.index('-----END CERTIFICATE-----')+1)
+    ])
+