TST/ERR: raise a ValueError at runtime for incompatible versions of openpyxl

instead of warning at import time

add openpyxl 2.0.3 to trigger travis fails on import
Merge pull request #7285 from cpcloud/openpyxl-format-string-fix-7284

BUG/CI/TST: fix format strings
BUG: BoolBlock shouldn't replace truthy values
Merge pull request #7304 from cpcloud/fix-replace-bool-yet-again-7140

BUG: replace() alters unrelated values
BUG: union should not try to sort inplace because platform impls differ as to when sorting occurs for objects that cannot be compared
TST: Assert that a RuntimeWarning is triggered
TST: should not warn on PY3 bc tp_compare was removed
WRN: warn about sorting inplace for non-comparable types
TST/CLN: make sure RuntimeWarning is raised
WRN: warn on copying sort
BUG/TST: DatetimeIndex has join precedence over Int64Index
BUG/DUH: don't copy just check the first value

of each self and other throw a type error on ``<``,
if not we can sort inplace on the concat, otherwise we issue a warn and make no
changes
BUG: variable not defined in exception
BUG: have to use the other_diff
TST/ERR: test warnings for unsortable dtypes
BUG: compare values not boxed objects
BUG/COMPAT: reduce from compat