Use pyomo.common.dependencies.attempt_import to resolve test_imports …

…failure

idaes/models_extra/temperature_swing_adsorption/fixed_bed_tsa0d_ui.py

@@ -17,9 +17,13 @@
 """
 UI exports for 0D Fixed Bed TSA unit model.
 """
-
 from pyomo.environ import ConcreteModel, SolverFactory, units
-from idaes_flowsheet_processor import api
+from pyomo.common.dependencies import attempt_import
+
+api, flowsheet_processor_available = attempt_import(
+    "idaes_flowsheet_processor.api", defer_import=False
+)
+
 from idaes.core import FlowsheetBlock
 from idaes.core.util.model_statistics import degrees_of_freedom
 import idaes.core.util as iutil