[chronik-client] Bump axios to ^1.18.0 for proxy inheritance fix

Summary: Raise axios from ^1.16.1 to ^1.18.0 in chronik-client, cashtab-faucet, ecash-herald, and token-server to clear GHSA-gcfj-64vw-6mp9 (high) and related moderate axios advisories.

Test Plan:

• pnpm install
• pnpm audit (axios advisories gone; 55→45 vulns, high 17→16, moderate 26→17)
• cd modules/chronik-client && NODE_PATH=../../node_modules pnpm test # 23 passing

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D20349