fix: correct NODE_SHEBANG regex escaping in doctest rule

Forward slashes inside the regex literal must be escaped as \/ to avoid
prematurely terminating the regex delimiter. The prior push omitted the
backslashes, producing a syntax error that broke module loading.

Author: Planeshifter

lib/node_modules/@stdlib/_tools/eslint/rules/doctest/lib/main.js

@@ -50,7 +50,7 @@ var RE_ESLINT_INLINE = / ?\/\/ eslint-disable-(?:next-)?line[^\n]*\n/g;
 var RE_NEWLINE = /\r?\n/g;
 var RE_ANNOTATION = /(?:\n|^)(?:var|let|const)? ?(?!function\b)([a-zA-Z0-9._]+) ?=?[^;]*;\n\/\/ ?(returns|([A-Za-z][A-Za-z_0-9]*)? ?=>|throws) {0,1}([\s\S]*?)(\n|$)/g;
 var RE_CONSOLE = /console\.(?:dir|error|log)/;
-var NODE_SHEBANG = /#!/usr/bin/env node/;
+var NODE_SHEBANG = /#!\/usr\/bin\/env node/;
 var rule;