Suppress codespell complaints about "SEH"

For now just exclude the line with it, but we may need to give up and
ignore "seh" as a word if this continues, as it just occurs in too many
places.

misc/suppressions/codespell-lines

@@ -23,3 +23,4 @@ expressions</em> (BRE). EREs are roughly those of the traditional @e egrep,
 // Purpose:     declarations for SEH (structured exceptions handling) support
     // 2019), i.e. SEH translator seems to work just fine without /EHa too, so
 // Purpose:     helpers for the structured exception handling (SEH) under Win32
+* MinGW-w64 versions 7.3 and 8.1 (32-bit binaries use SJLJ exceptions, 64-bit ones use SEH, and all binaries use Win32 threads).