TypeError when subtracting datetime64 and timestamp but only in eval
#### Code Sample

```python
import pandas as pd
pd.show_versions()

today = pd.to_datetime("today")
df = pd.DataFrame({'date': [today]})

assert isinstance(today, pd.Timestamp)
assert str(df.date.dtype) == 'datetime64[ns]'

delta = df.date - today  # works fine
assert str(delta.dtype) == 'timedelta64[ns]'

df.eval("date - @today")  # fails
```

Live demo: https://repl.it/repls/SelfassuredFrighteningNumber

#### Problem description

Subtraction works 'normally' but not when used inside DataFrame.eval or .query. AFAIK the two methods should be equivalent. eval fails with:

```python
Traceback (most recent call last):
  File "main.py", line 13, in <module>
    df.eval("date - @today")  # fails
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/frame.py", line 3315, in eval
    return _eval(expr, inplace=inplace, **kwargs)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/eval.py", line 322, in eval
    parsed_expr = Expr(expr, engine=engine, parser=parser, env=env, truediv=truediv)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 830, in __init__
    self.terms = self.parse()
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 847, in parse
    return self._visitor.visit(self.expr)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 441, in visit
    return visitor(node, **kwargs)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 447, in visit_Module
    return self.visit(expr, **kwargs)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 441, in visit
    return visitor(node, **kwargs)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 450, in visit_Expr
    return self.visit(node.value, **kwargs)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 441, in visit
    return visitor(node, **kwargs)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 565, in visit_BinOp
    return self._maybe_evaluate_binop(op, op_class, left, right)
  File "/home/runner/.local/share/virtualenvs/python3/lib/python3.7/site-packages/pandas/core/computation/expr.py", line 536, in _maybe_evaluate_binop
    " '{lhs}' and '{rhs}'".format(op=res.op, lhs=lhs.type, rhs=rhs.type)
TypeError: unsupported operand type(s) for -: 'datetime64[ns]' and '<class 'pandas._libs.tslibs.timestamps.Timestamp'>'
```

#### Output of ``pd.show_versions()``

<details>


INSTALLED VERSIONS
------------------
commit           : None
python           : 3.7.4.final.0
python-bits      : 64
OS               : Linux
OS-release       : 4.15.0-1036-gcp
machine          : x86_64
processor        :
byteorder        : little
LC_ALL           : None
LANG             : C.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 0.25.3numpy            : 1.18.0
pytz             : 2019.3
dateutil         : 2.8.1pip              : 19.0.3
setuptools       : 40.8.0
Cython           : Nonepytest           : None
hypothesis       : None
sphinx           : Noneblosc            : None
feather          : None
xlsxwriter       : Nonelxml.etree       : None
html5lib         : None
pymysql          : Nonepsycopg2         : None
jinja2           : None
IPython          : Nonepandas_datareader: None
bs4              : None
bottleneck       : Nonefastparquet      : None
gcsfs            : None
lxml.etree       : None
matplotlib       : 3.1.1
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pytables         : None
s3fs             : None
scipy            : 1.3.1
sqlalchemy       : None
tables           : None
xarray           : None
xlrd             : None
xlwt             : None
xlsxwriter       : None
</details>
