PYCBC-1775: Maybe unshallow repo in performer docker build

Motivation
==========
On the CI workflow building the performer docker image, the git repo is shallow cloned with no tags or commit history. This means that couchbase_version.py is unable to determine the version of the SDK.

Changes
=======
In the performer Dockerfile, fetch the commit history & tags before building the SDK (git fetch --unshallow --tags)

Change-Id: I58b520f41cfddb30f8705c8c6bbeb69d6f9c1d09
Reviewed-on: https://review.couchbase.org/c/couchbase-python-client/+/250810
Reviewed-by: Jared Casey <jared.casey@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>

Author: DemetrisChr

tools/fit_performer/Dockerfile

@@ -21,6 +21,15 @@ RUN if [ ! -f deps/couchbase-cxx-client/CMakeLists.txt ]; then \
              "the SDK build below will fail without it."; \
     fi
 
+# CI checks out repo with no tags or commit history history, so unshallow the repo here.
+# This is to ensure couchbase_version.py is able to determine the version of the SDK.
+RUN if [ "$(git rev-parse --is-shallow-repository)" = "true" ]; then \
+        echo "Shallow checkout detected, fetching history and tags..."; \
+        git fetch --unshallow --tags --no-recurse-submodules origin; \
+    else \
+        echo "Full checkout detected, no need to fetch history or tags."; \
+    fi;
+
 RUN PYCBC_USE_CPM_CACHE=false pip install .
 
 WORKDIR /app/tools/fit_performer