python3: run-clang-tidy conversion

Upstream has not switched run-clang-tidy over to python3 yet but they
have done the changes needed to support it. OpenBMC is done with python2
so move clang-tidy over to python3 until upstream has an official change
for it.

Resolves openbmc/phosphor-state-manager#13

Tested:
Verified this change fixed the issue above and phosphor-state-manager
once again passes CI tests

Change-Id: I519270eb69db723c9a564bb05b67744d28851850
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/build-unit-test-docker.sh b/build-unit-test-docker.sh
index 9920131..87017d5 100755
--- a/build-unit-test-docker.sh
+++ b/build-unit-test-docker.sh
@@ -250,6 +250,10 @@
 RUN pip3 install jsonschema
 RUN pip3 install meson==0.53.2
 
+# run-clang-tidy-8.py has not moved to python3 yet however it
+# supports it for our needs to just switch it over
+RUN sed -i '1s/python$/python3/' /usr/bin/run-clang-tidy-8.py
+
 FROM openbmc-base as openbmc-lcov
 RUN curl -L https://github.com/linux-test-project/lcov/archive/${PKG_REV['lcov']}.tar.gz | tar -xz && \
 cd lcov-* && \