opts_string for externalized tables

[hgroll]

Hello,
In case the save argument "externalize_tables" is set to True, the constructed string "opts_str" is not replaced as the variable "opts_string" is expected in the f-string:

tikzplotlib/src/tikzplotlib/_line2d.py

Line 293 in fe5dcf5

content.append(f"table {{opts_string}}{{{posix_filepath}}};\n")

[7Z0t99]

Please reopen this issue. As commented at 1b261f4 , the merged pull request #539 does not fix the issue. A potential solution is also proposed at 1b261f4 .