fix handling of bytes outside ASCII range (#975)

spec/avram/queryable_spec.cr

@@ -1229,6 +1229,16 @@ describe Avram::Queryable do
         Beat::BaseQuery.new.hash(Bytes.empty).select_count.should eq(0)
       end
     end
+
+    context "binary data query" do
+      it "returns the correct result" do
+        hash = Bytes[0, 1, 2, 256]
+        BeatFactory.create &.hash(hash)
+
+        Beat::BaseQuery.new.hash(hash).select_count.should eq(1)
+        Beat::BaseQuery.new.hash(Bytes.empty).select_count.should eq(0)
+      end
+    end
   end
 
   describe ".truncate" do

src/avram/charms/slice_extensions.cr

@@ -24,7 +24,13 @@ struct Slice(T)
     end
 
     def to_db(value : Bytes)
-      String.new(value)
+      ssize = value.size * 2 + 2
+      String.new(ssize) do |buffer|
+        buffer[0] = '\\'.ord.to_u8
+        buffer[1] = 'x'.ord.to_u8
+        value.hexstring(buffer + 2)
+        {ssize, ssize}
+      end
     end
 
     def to_db(value : String) : String