run.bat: check go.exe instead of go
run.bat: check go.exe instead of go

Windows requires checking with the .exe extension.

Change-Id: I8e2fe83df81b92f04967bafb28f8effde999f597
Reviewed-on: https://go-review.googlesource.com/c/go/+/227157
Reviewed-by: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Run-TryBot: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

akutz/go,akutz/go,golang/go,akutz/go,golang/go,CAFxX/go,akutz/go,cloudflare/go,nawawi/go,akutz/go,cloudflare/go,cloudflare/go,nawawi/go,golang/go,nawawi/go,golang/go,nawawi/go,nawawi/go,CAFxX/go,cloudflare/go,golang/go,CAFxX/go,cloudflare/go,golang/go,akutz/go,akutz/go,CAFxX/go,cloudflare/go,golang/go,CAFxX/go,nawawi/go,CAFxX/go,akutz/go,CAFxX/go,cloudflare/go,nawawi/go,cloudflare/go,CAFxX/go,nawawi/go,golang/go