Unable to use CSRF middleware
Maybe I'm doing it wrong.

In my form generation I put the following code (it's a Source Code Filter):

```nim
#? stdtmpl | standard
#import prologue/middlewares/csrf
#
#proc alignForm(ctx: Context): string =                                         
#  result = "" 
<form method="post">
  csrfToken(ctx)
<-- All other inputs -->
</form>
#end proc
```

This fails to create the CSRF token with

```
index 32 not in 0 .. 31
[...]
  /home/xbello/.nimble/pkgs/prologue-0.3.2/prologue/middlewares/csrf.nim(52)     makeToken
  /home/xbello/.choosenim/toolchains/nim-1.2.6/lib/system/fatal.nim(49)          sysFatal
[...]
```

So this traced the index failure to the line 52 in prologue/middlewares/csrf.nim, that is:

`token[idx] = mask[idx] + secret[idx]`

but it turns out that both `mask` and `secret` have a length of 32 elements, as both of them are created with size `
DefaultSecretSize` (32).

I changed the above line to:

`token[idx] = mask[idx - DefaultSecretSize] + secret[idx - DefaultSecretSize]`

And it seems to work now. But I'm no expert in security, so I'm not 100% sure it it makes sense. The CSRF cookie seems to be correctly created and set.