Fix "grep: warning: stray \ before -" in `conda.bash` (#2768)

According to the POSIX spec, an unescaped backslash not followed by
an escapable character is undefined behavior,
and it has become an error in GNU grep 3.8 (2022-09-02).

pyenv.d/rehash/conda.bash

@@ -35,7 +35,7 @@ make_shims() {
 
 deregister_conda_shims() {
   # adapted for Bash 4.x's associative array (#1749)
-  if declare -p registered_shims 2> /dev/null | grep -Eq '^(declare|typeset) \-A'; then
+  if declare -p registered_shims 2> /dev/null | grep -Eq '^(declare|typeset) -A'; then
     for shim in ${!registered_shims[*]}; do
       if conda_shim "${shim}" 1>&2; then
         unset registered_shims[${shim}]