Prevent grep warning in conda.bash
I was getting warnings when running various `pyenv` commands because of
an improper call to `grep`:
```
$ grep -Eq '^(declare|typeset) \-A' </dev/null
grep: warning: stray \ before -
$ grep -Eq '^(declare|typeset) -A' </dev/null
```
This call was added in dfeda54,[^1] and there is no documented reason
for having the `\`.
According to the GNU grep manual:[^2]
> The behavior of `grep` is unspecified if a unescaped backslash is not
> followed by a special character, a nonzero digit, or a character in
> the above list. Although `grep` might issue a diagnostic and/or give
> the backslash an interpretation now, its behavior may change if the
> syntax of regular expressions is extended in future versions.
This became an error in GNU grep 3.8 (2022-09-02),[^3] which explains
why this problem was not found when the original code was added. This
undefined behavior is part of the POSIX spec,[^4] so this fix should not
break any other versions of `grep` being used.
[^1]:
dfeda54079
[^2]:
https://www.gnu.org/software/grep/manual/grep.html#Special-Backslash-Expressions
(Permalink: https://git.savannah.gnu.org/cgit/grep.git/tree/doc/grep.texi?id=d1c3fbe7722662b449bae23130b644c726473fe3#n1528)
[^3]:
https://savannah.gnu.org/news/?id=10191
(Permalink: https://git.savannah.gnu.org/cgit/grep.git/tree/NEWS?id=d1c3fbe7722662b449bae23130b644c726473fe3#n99)
[^4]:
https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04_02,
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html
57b5341e06