fix: shbangs in bash configuration files

.bash_logout

@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+#!/bin/bash
 #
 # ~/.bash_logout
 # sourced when an interactive login shell exits, or a non-interactive login shell executes `exit`

.bash_profile

@@ -1,4 +1,4 @@
-# shellcheck shell=bash
+#!/bin/bash
 # shellcheck disable=1091
 #
 # ~/.bash_profile

.bashrc

@@ -1,5 +1,5 @@
-# shellcheck shell=bash
+#!/bin/bash
-# shellcheck disable=SC1090,SC1091
+# shellcheck disable=SC1091,SC2155
 #
 # ~/.bashrc
 # sourced upon launch of an interactive shell, which isn't a login shell has been executed