DP Lib 1.1.1

This patch release only affects the C++ DP Lib.

We fixed the implicit approximate bounds use case for multiple contributions for sum, mean. variance, and stddev, i.e., when neither approximate bounds, nor upper/lower limits have been set in the builder. Since the approx bounds algorithm just provides the sensitivity for a subsequently executed algorithm, this might not be catastrophic and still provides differentially private outputs with a slightly increased privacy loss.