fix(bm): Board Manager install will fail on Windows

On some Windows installations, Board Manager will fail to install the RC2 core, because it could not find esptool for the given OS.

Author: me-no-dev

Diff for: package/package_esp32_index.template.json

@@ -490,6 +490,13 @@
               "checksum": "SHA-256:6e1fc5ea04490e849c925c48d5cee590164fcf9b9bd419a7b014c2fb48a13743",
               "size": "29828542"
             },
+            {
+              "host": "i686-mingw32",
+              "url": "https://github.com/espressif/arduino-esp32/releases/download/3.1.0-RC1/esptool-v4.8.1-win64.zip",
+              "archiveFileName": "esptool-v4.8.1-win64.zip",
+              "checksum": "SHA-256:3e97fb990fdd721b923b478eaaa046967c7919dbc9cbd04c445307571177918a",
+              "size": "33612728"
+            },
             {
               "host": "x86_64-mingw32",
               "url": "https://github.com/espressif/arduino-esp32/releases/download/3.1.0-RC1/esptool-v4.8.1-win64.zip",