fix: using not contains query filter

We were using `not_contains` as the function name in DynamoDB filter
expressions, but DynamoDB throws an error `Invalid FilterExpression:
Invalid function name; function: not_contains`. The proper function name
is simply `not contains`.

src/query/expression.spec.ts

@@ -253,6 +253,21 @@ describe('query/expression', () => {
           ':v1': { BOOL: true },
         },
       })
+
+      expect(buildQueryExpression(schema, {
+        someString: ['not contains', 'hello world'],
+        someBool: true,
+      })).to.deep.equal({
+        FilterExpression: 'not contains(#a0, :v0) AND #a1 = :v1',
+        ExpressionAttributeNames: {
+          '#a0': 'someString',
+          '#a1': 'someBool',
+        },
+        ExpressionAttributeValues: {
+          ':v0': { S: 'hello world' },
+          ':v1': { BOOL: true },
+        },
+      })
     })
 
     it('works with includes/IN operator', () => {

src/query/expression.ts

@@ -262,7 +262,7 @@ class FilterExpressionQuery<T extends Table> {
           strValue = { B: _.isArray(strValue.BS) ? strValue.BS[0] : strValue.BS }
         }
 
-        const queryOperator = operator === 'beginsWith' ? 'begins_with' : operator.replace(/ /g, '_')
+        const queryOperator = operator === 'beginsWith' ? 'begins_with' : operator
         query = `${queryOperator}(${attrNameMappedTo}, ${variableName})`
         values[variableName] = strValue
         break