Bump minimal Bash version from 2.05 to 3.0

This is required by the use of `<<<` to compose the `S2_*` and `ax_*`
arrays.

I could use here-docs `<<` instead, but there's another reason to bump
this version: the oldest supported version in the official Docker image
for Bash is 3.0.

So getting an old 2.05 and put automated tests for it would be a
deviation for the procedure already in place for all the other versions.

Version 2.05 is from 2001 and 3.0 is from 2004. We're still supporting a
very old version anyway.

Now every supported Bash version is properly tested in the CI.

CHANGELOG.md

@@ -55,7 +55,7 @@ The format is based on [Keep a Changelog].
 
 ### Changed
 
-- Bumped minimal required Bash version from 2.04 to 2.05
+- Bumped minimal required Bash version from 2.04 to 3.0
 - Bumped the versions for all the supported programs
 - Validated and updated the regex data for all the supported programs,
   thanks to the new regex tester. Some programs now support new

README.md

@@ -5,7 +5,7 @@
 - Author: [Aurelio Jargas](https://aurelio.net/about.html)
 - License: GPL
 - First release: 2001-02-23
-- Requires: Bash >= 2.05
+- Requires: Bash >= 3.0
 - Website: https://aurelio.net/projects/txt2regex/
 
 Txt2regex is a regular expression wizard that converts human sentences

txt2regex.sh

@@ -1,10 +1,10 @@
 #!/bin/bash
-# txt2regex.sh - Regular Expressions "wizard", all in bash2 builtins
+# txt2regex.sh - Regular Expressions "wizard" made with Bash builtins
 #
 # Website : https://aurelio.net/projects/txt2regex/
 # Author  : Aurelio Jargas ([email protected])
 # License : GPL
-# Requires: bash >= 2.05
+# Requires: bash >= 3.0
 #
 # shellcheck disable=SC1117,SC2034
 #   SC1117 because it was obsoleted in shellcheck >0.5
@@ -96,11 +96,11 @@ printError() {
 }
 
 case "$BASH_VERSION" in
-    2.0[5-9]* | 2.[1-9]* | [3-9].*)
+    [3-9].*)
         : # do nothing
         ;;
     *)
-        printError 'Bash version >=2.05 required, but you have %s\n' "$BASH_VERSION"
+        printError 'Bash version >=3.0 required, but you have %s\n' "$BASH_VERSION"
         ;;
 esac