scripts: csv.py: Fixed completely broken float parsing

Whoops! A missing splat repetition here meant we only ever accepted
floats with a single digit of precision and no e/E exponents.

Humorously this went unnoticed because our scripts were only
_outputting_ single digit floats, but now that that's fixed, float
parsing also needs a fix.

Fixed by allowing >1 digit of precision in our CsvFloat regex.

scripts/csv.py

@@ -1129,7 +1129,7 @@ class CsvExpr:
                 p.chomp()
 
             # floats
-            elif p.match('[+-]?(?:[_0-9]*\.[_0-9eE]|nan)'):
+            elif p.match('[+-]?(?:[_0-9]*\.[_0-9eE]*|nan)'):
                 a = CsvExpr.FloatLit(CsvFloat(p.chomp()))
 
             # ints