Remove duplicate target from ci/build.sh

I'm almost certain this is not intentional

Author: alex

ci/build.sh

@@ -201,7 +201,6 @@ thumbv8m.main-none-eabi \
 x86_64-pc-windows-msvc
 x86_64-unknown-bitrig \
 x86_64-unknown-dragonfly \
-x86_64-unknown-dragonfly \
 x86_64-unknown-haiku \
 x86_64-unknown-hermit \
 x86_64-unknown-l4re-uclibc \