Fix RPC TestEth_GetFilterChanges_* tests

[jbowen93]

The following RPC Tests fail

• TestEth_GetFilterChanges_BlockFilter

=== RUN   TestEth_GetFilterChanges_BlockFilter
    assertion_compare.go:323:
        	Error Trace:	rpc_test.go:225
        	Error:      	"0" is not greater than or equal to "1"
        	Test:       	TestEth_GetFilterChanges_BlockFilter
        	Messages:   	[]
--- FAIL: TestEth_GetFilterChanges_BlockFilter (5.55s)

• TestEth_GetFilterChanges_NoTopics

=== RUN   TestEth_GetFilterChanges_NoTopics
    rpc_test.go:298:
        	Error Trace:	rpc_test.go:298
        	            				rpc_test.go:352
        	Error:      	Expected value not to be nil.
        	Test:       	TestEth_GetFilterChanges_NoTopics
        	Messages:   	transaction failed
--- FAIL: TestEth_GetFilterChanges_NoTopics (16.56s)

• TestEth_GetFilterChanges_Topics_AB

=== RUN   TestEth_GetFilterChanges_Topics_AB
    rpc_test.go:439:
        	Error Trace:	rpc_test.go:439
        	Error:      	Not equal:
        	            	expected: 1
        	            	actual  : 0
        	Test:       	TestEth_GetFilterChanges_Topics_AB
--- FAIL: TestEth_GetFilterChanges_Topics_AB (10.55s)

• TestEth_GetFilterChanges_Topics_XB

=== RUN   TestEth_GetFilterChanges_Topics_XB
    rpc_test.go:405:
        	Error Trace:	rpc_test.go:405
        	            				rpc_test.go:460
        	Error:      	Expected value not to be nil.
        	Test:       	TestEth_GetFilterChanges_Topics_XB
        	Messages:   	transaction failed
--- FAIL: TestEth_GetFilterChanges_Topics_XB (18.60s)