Remove deceiving tag on mbedtls .gitmodules file

The mbedtls submodule is pinned to v3 but the tag pointed to v2

Author: jgmdev

.gitmodules

@@ -18,7 +18,6 @@
 [submodule "lib/mbedtls"]
 	path = lib/mbedtls
 	url = https://github.com/Mbed-TLS/mbedtls.git
-	tag = mbedtls-2.28.3
 	shallow = true
 [submodule "lib/xz"]
 	path = lib/xz