fix Illegal quoting

When viewed on GitHub,
[summary.csv](https://github.com/ioccc-src/temp-test-ioccc/blob/master/summary.csv)
reported:

> We can make this file beautiful and searchable if this error is corrected: Illegal quoting in line 16.

This is an attempt to fix that problem.

NOTE: We are not sure what is wrong with the quotes on line 16.
Perhaps any quotes with the file is a problem and GitHub just reported
the first problem?

summary.csv

@@ -13,7 +13,7 @@
 1986,bright,bright.1986,hex dump with cpp compressed that uses lots of << for constants
 1986,hague,hague.1986,morse code filter written with 'DIT DAH _DIT DIT_DAH'
 1986,holloway,holloway.1986,prints hello world! via a recursive main
-1986,marshall,marshall.1986,train engine-shaped program prints "choo choo"
+1986,marshall,marshall.1986,train engine-shaped program prints choo choo
 1986,pawka,pawka.1986,prints 'obfuscated?' big using xyyyx idents
 1986,stein,stein.1986,prints HHMMSS in UTC time
 1986,wall,wall.1986,dvorak keyboard emulator