Fix 'equals' predicate in SpatialJoin

This fixes a typo in SpatialJoin.py "Join attributes by location" algorithm that prevents the 'equals' predicate to work

(cherry picked from commit abd4d0e)

Author: agiudiceandrea

python/plugins/processing/algs/qgis/SpatialJoin.py

@@ -72,7 +72,7 @@ def initAlgorithm(self, config=None):
         self.predicates = (
             ('intersects', self.tr('intersects')),
             ('contains', self.tr('contains')),
-            ('equals', self.tr('equals')),
+            ('isEqual', self.tr('equals')),
             ('touches', self.tr('touches')),
             ('overlaps', self.tr('overlaps')),
             ('within', self.tr('within')),