[SEBA-946]

Fix documentation job by using the maintained fork of linkchecker rather
than abandoned version in pypi

Change-Id: Iaaff8059eac4cd40a9b703c2cbc776afa636fbd8
diff --git a/packer/provision/basebuild.sh b/packer/provision/basebuild.sh
index c433d2d..41c358c 100644
--- a/packer/provision/basebuild.sh
+++ b/packer/provision/basebuild.sh
@@ -146,7 +146,7 @@
         grpcio-tools \
         httpie==1.0.3 \
         isort \
-        linkchecker \
+        git+https://github.com/linkchecker/linkchecker.git@v9.4.0 \
         more-itertools==5.0.0 \
         mock \
         netaddr \