Bump grpc to 1.45.2, clean up transaction

conanfile.py

include/caosdb/authentication.h

include/caosdb/entity.h

include/caosdb/transaction.h

src/caosdb/authentication.cpp

src/caosdb/connection.cpp

src/caosdb/transaction.cpp

test/test_entity.cpp

test/test_issues.cpp

test/test_transaction.cpp