Revert ".net framework upgraded for Database project"

This reverts commit 1de36ca.

Author: swapnamol-abraham

WebAPI/LearningHub.Nhs.Database/LearningHub.Nhs.Database.sqlproj

@@ -16,7 +16,7 @@
     <ModelCollation>1033, CI</ModelCollation>
     <DefaultFileStructure>BySchemaAndSchemaType</DefaultFileStructure>
     <DeployToDatabase>True</DeployToDatabase>
-    <TargetFrameworkVersion>v4.8</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.5.2</TargetFrameworkVersion>
     <TargetLanguage>CS</TargetLanguage>
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <SqlServerVerification>False</SqlServerVerification>