boost: 1.69.0 -> 1.71.0

bmcweb requires boost 1.71 or newer, and it could be better to provide
bmcweb's necessary environment in local CI, so that it could be built
without 3rd-party dependencies.

Tested: Build bmcweb in local CI with YOCTO_DEPENDENCIES enabled.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I01710951b3b8aa157d6c2708d1d3ae804f6aa890
diff --git a/build-unit-test-docker.sh b/build-unit-test-docker.sh
index 899cd89..84a378c 100755
--- a/build-unit-test-docker.sh
+++ b/build-unit-test-docker.sh
@@ -91,7 +91,7 @@
 # A list of package versions we are building
 # Start off by listing the stating versions of third-party sources
 declare -A PKG_REV=(
-  [boost]=1.69.0
+  [boost]=1.71.0
   [cereal]=v1.2.2
   [catch2]=v2.10.0
   [CLI11]=v1.8.0