Surrounding the T with single quotes should work:
yyyy-MM-dd'T'hh:mm:ssZ
Quoting from the documentation (emphasis mine):
Date and time formats are specified by date and time pattern strings. Within date and time pattern strings, unquoted letters from
'A'to'Z'and from'a'to'z'are interpreted as pattern letters representing the components of a date or time string. Text can be quoted using single quotes (') to avoid interpretation."''"represents a single quote. All other characters are not interpreted; they’re simply copied into the output string during formatting or matched against the input string during parsing.
Your specific use case is even included as an example:
Date and Time Pattern Result
-------------------------------------------------------------
"yyyy-MM-dd'T'HH:mm:ss.SSSZ" 2001-07-04T12:08:56.235-0700