build: bump golang 1.20.2 -> 1.20.3

This Go release includes the following security fixes:

* CVE-2023-24537
* CVE-2023-24538
* CVE-2023-24534
* CVE-2023-24536

https://groups.google.com/g/golang-announce/c/Xdv6JL9ENs8

Signed-off-by: Ashutosh Narkar <anarkar4387@gmail.com>