Revert 'go get -u' on psiphon-tunnel-core/psiphon

The working directory is passed into the build as a detached head (in some CI servers), and then the -u tries to force an upgrade, which go get doesn't like

The `./...` was broken due to everything moving one level deeper in the path (tested `../...` and it worked), but is covered more clearly by `go get github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon` which pulls all the dependencies without forcing psiphon itself to upgrade

MobileLibrary/Android/make.bash

@@ -8,7 +8,7 @@ if [ ! -f make.bash ]; then
 fi
 
 GOOS=arm go get -d -v -u github.com/Psiphon-Inc/openssl
-GOOS=arm go get -d -v -u github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon
+GOOS=arm go get -d -v github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon
 if [ $? != 0 ]; then
   echo "..'go get' failed, exiting"
   exit $?