Use Temporary Directory in Docs Example For Dim Labels (#1815)

* When running tests locally, the example array gets created but does
not get deleted. This results in  subsequent test runs erroring out
because it tries to create the array again, but it already exists.

Author: nguyenv

tiledb/libtiledb.pyx

@@ -1512,22 +1512,22 @@ cdef class Array(object):
         ...     },
         ... }
         >>> schema = tiledb.ArraySchema(domain=dom, attrs=(att,), dim_labels=dim_labels)
-        >>> uri = "label_index_example"
-        >>> tiledb.Array.create(uri, schema)
-        >>>
-        >>> a1_data = np.reshape(np.arange(1, 13), (4, 3))
-        >>> l1_data = np.arange(4, 0, -1)
-        >>> l2_data = np.arange(-1, 2)
-        >>> l3_data = np.linspace(0, 1.0, 3)
-        >>>
-        >>> with tiledb.open(uri, "w") as A:
-        ...     A[:] = {"a1": a1_data, "l1": l1_data, "l2": l2_data, "l3": l3_data}
-        >>>
-        >>> with tiledb.open(uri, "r") as A:
-        ...     A.label_index(["l1"])[3:4]
-        ...     A.label_index(["l1", "l3"])[2, 0.5:1.0]
-        ...     A.label_index(["l2"])[:, -1:0]
-        ...     A.label_index(["l3"])[:, 0.5:1.0]
+        >>> with tempfile.TemporaryDirectory() as tmp:
+        ...     tiledb.Array.create(tmp, schema)
+        ...
+        ...     a1_data = np.reshape(np.arange(1, 13), (4, 3))
+        ...     l1_data = np.arange(4, 0, -1)
+        ...     l2_data = np.arange(-1, 2)
+        ...     l3_data = np.linspace(0, 1.0, 3)
+        ...
+        ...     with tiledb.open(tmp, "w") as A:
+        ...         A[:] = {"a1": a1_data, "l1": l1_data, "l2": l2_data, "l3": l3_data}
+        ...
+        ...     with tiledb.open(tmp, "r") as A:
+        ...         A.label_index(["l1"])[3:4]
+        ...         A.label_index(["l1", "l3"])[2, 0.5:1.0]
+        ...         A.label_index(["l2"])[:, -1:0]
+        ...         A.label_index(["l3"])[:, 0.5:1.0]
         OrderedDict([('l1', array([4, 3])), ('a1', array([[1, 2, 3],
                [4, 5, 6]]))])
         OrderedDict([('l3', array([0.5, 1. ])), ('l1', array([2])), ('a1', array([[8, 9]]))])