refactor: follow clippy recommendation :

- Remove unused constructor for Table & Column
- Add .expect in databases. disconnect
- Remove usedless String::from in column serializer

src/schemas/builders.rs

@@ -84,6 +84,12 @@ impl ColumnBuilder {
     }
 }
 
+impl Default for ColumnBuilder {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 pub struct TableBuilder {
     name: String,
     columns: Vec<Column>,
@@ -119,6 +125,12 @@ impl TableBuilder {
     }
 }
 
+impl Default for TableBuilder {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 #[cfg(test)]
 mod test {
     use crate::mappings::SQLiteDatatypes;