fix(SC3003)!: remove SC3003 since ANSI C string is defined in POSIX.1-2024

https://pubs.opengroup.org/onlinepubs/9799919799/utilities/V3_chap02.html#tag_19_02_04

dash v0.5.13 supports the feature

resolve #1678, resolve #3098

Author: e-kwsm

CHANGELOG.md

@@ -6,6 +6,7 @@
 ### Fixed
 
 ### Removed
+- SC3003: removed since ANSI C string is specified in POSIX.1-2024
 
 
 ## v0.11.0 - 2025-08-03

src/ShellCheck/Checks/ShellSupport.hs

@@ -213,7 +213,7 @@ prop_checkBashisms118 = verify checkBashisms "#!/bin/busybox sh\nxyz=1\n${!x*}"
 prop_checkBashisms119 = verify checkBashisms "#!/bin/busybox sh\nx='test'\n${x^^[t]}" -- SC3059
 prop_checkBashisms120 = verify checkBashisms "#!/bin/sh\n[ x == y ]"
 prop_checkBashisms121 = verifyNot checkBashisms "#!/bin/sh\n# shellcheck shell=busybox\n[ x == y ]"
-prop_checkBashisms122 = verify checkBashisms "#!/bin/dash\n$'a'"
+prop_checkBashisms122 = verifyNot checkBashisms "#!/bin/dash\n$'a'"
 prop_checkBashisms123 = verifyNot checkBashisms "#!/bin/busybox sh\n$'a'"
 prop_checkBashisms124 = verify checkBashisms "#!/bin/dash\ntype -p test"
 prop_checkBashisms125 = verifyNot checkBashisms "#!/bin/busybox sh\ntype -p test"
@@ -240,8 +240,6 @@ checkBashisms = ForShell [Sh, Dash, BusyboxSh] $ \t -> do
 
     bashism (T_ProcSub id _ _) = warnMsg id 3001 "process substitution is"
     bashism (T_Extglob id _ _) = warnMsg id 3002 "extglob is"
-    bashism (T_DollarSingleQuoted id _) =
-        unless isBusyboxSh $ warnMsg id 3003 "$'..' is"
     bashism (T_DollarDoubleQuoted id _) = warnMsg id 3004 "$\"..\" is"
     bashism (T_ForArithmetic id _ _ _ _) = warnMsg id 3005 "arithmetic for loops are"
     bashism (T_Arithmetic id _) = warnMsg id 3006 "standalone ((..)) is"