initramfs-build: Add locales dependency

locale-gen is required to run the build.

Change-Id: I53818e9aaecfa6a6aa30ed58dbb347babe54fb49
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/initramfs-build.sh b/initramfs-build.sh
index bbbb67b..4c56730 100755
--- a/initramfs-build.sh
+++ b/initramfs-build.sh
@@ -32,7 +32,8 @@
 	python \
 	unzip \
 	wget \
-	iputils-ping
+	iputils-ping \
+	locales
 
 RUN grep -q ${GROUPS} /etc/group || groupadd -g ${GROUPS} ${USER}
 RUN grep -q ${UID} /etc/passwd || useradd -d ${HOME} -m -u ${UID} -g ${GROUPS} ${USER}