Disable encryption when using stub

Co-authored-by: Timothy Mertz <mertzt89@gmail.com>

Author: ryankurte

espflash/src/flash_target/esp32.rs

@@ -108,7 +108,7 @@ impl FlashTarget for Esp32Target {
                     blocks: block_count as u32,
                     block_size: FLASH_WRITE_SIZE as u32,
                     offset: addr,
-                    supports_encryption: self.chip != Chip::Esp32,
+                    supports_encryption: self.chip != Chip::Esp32 && !self.use_stub,
                 })?;
                 Ok(())
             },