inDateRange with only one date not working as expected

**Describe the bug**
As stated in the documentation ([operator inDateRange](https://cube.dev/docs/query-format#filters-operators-in-date-range)) _"If only one date specified the filter would be set exactly to this date"_.
Instead, it seems to consider the only date provided as a lower bound.

**To Reproduce**
```
{
member: "Posts.time",
operator: "inDateRange",
values: ['2015-01-01']
}
```

**Expected behavior**
Same as
```
{
member: "Posts.time",
operator: "inDateRange",
values: ['2015-01-01', '2015-01-01']
}
```
or
```
{
member: "Posts.time",
operator: "equals",
values: ['2015-01-01']
}
```

**Version:**
0.26.77