env/linux-arm64-bullseye: add GPG agent to the image

This change adds gpg-agent to the image used for linux-arm64-longtest.
TestScript/version_buildvcs_git_gpg is failing because it is missing.
This also adds gpg-agent and triggers a rebuild of the
linux-x86-bullseye image.

Upates golang/go#49649

Change-Id: I8adac58f21beeb7a1403d8d672b5a7409fd14f74
Reviewed-on: https://go-review.googlesource.com/c/build/+/453656
Reviewed-by: Carlos Amedee <[email protected]>
Run-TryBot: Carlos Amedee <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: cagedmantis

env/linux-arm64-bullseye/Dockerfile

@@ -39,6 +39,7 @@ RUN apt-get update && apt-get install -y \
 	gfortran \
 	git \
 	gpg \
+	gpg-agent \
 	iptables \
 	libc6-dev \
 	libgles2-mesa-dev \

env/linux-x86-bullseye/Dockerfile

@@ -45,6 +45,7 @@ RUN apt-get update && apt-get install -y \
 	gfortran-multilib \
 	git \
 	gpg \
+	gpg-agent \
 	iptables \
 	libc6-dev \
 	libc6-dev-i386 \