Clear api version when disconnecting. (#382)

Closes #354

app/src/main/java/apps/amine/bou/readerforselfoss/utils/Config.kt

@@ -51,6 +51,7 @@ class Config(c: Context) {
             editor.remove("url")
             editor.remove("login")
             editor.remove("password")
+            editor.remove("apiVersionMajor")
             editor.apply()
             val intent = Intent(c, LoginActivity::class.java)
             if (baseUrlFail) {