Add libgpiod-dev into docker container

This allows us to use libgpiod.

Tested: review 22115 built successfully

Change-Id: I493090b61bbcd9c451fe65ba35c9fe8bf9f5e1c1
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/build-unit-test-docker.sh b/build-unit-test-docker.sh
index 53e60bb..114b46f 100755
--- a/build-unit-test-docker.sh
+++ b/build-unit-test-docker.sh
@@ -216,7 +216,8 @@
     wget \
     libldap2-dev \
     libprotobuf-dev \
-    protobuf-compiler
+    protobuf-compiler \
+    libgpiod-dev
 
 RUN pip install inflection
 RUN pip install pycodestyle