Pin Node base image to version 20 to fix uWS incompatibility with latest LTS release

[mchris86]

Description

This PR fixes build failures in the server and worker containers caused by the use of Node v22, which is incompatible with the uws library used in this project.

The Dockerfile previously used:

FROM node:lts-alpine3.19

The lts tag currently resolves to Node.js v22 which causes the following runtime error:

worker-1  | /usr/src/app/node_modules/uws/uws.js:22
worker-1  |             throw new Error('This version of uWS.js supports only Node.js LTS versions 16, 18 and 20 on (glibc) Linux, macOS and Windows, on Tier 1 platforms (https://github.com/nodejs/node/blob/master/BUILDING.md#platform-list).\n\n' + e.toString());
worker-1  |                   ^
worker-1  | 
worker-1  | Error: This version of uWS.js supports only Node.js LTS versions 16, 18 and 20 on (glibc) Linux, macOS and Windows, on Tier 1 platforms (https://github.com/nodejs/node/blob/master/BUILDING.md#platform-list).
worker-1  | 
worker-1  | Error: Cannot find module './uws_linux_x64_127.node'
worker-1  | Require stack:
worker-1  | - /usr/src/app/node_modules/uws/uws.js
worker-1  |     at /usr/src/app/node_modules/uws/uws.js:22:9
worker-1  |     at Object.<anonymous> (/usr/src/app/node_modules/uws/uws.js:24:3)
worker-1  |     at Module._compile (node:internal/modules/cjs/loader:1565:14)
worker-1  |     at Object..js (node:internal/modules/cjs/loader:1708:10)
worker-1  |     at Module.load (node:internal/modules/cjs/loader:1318:32)
worker-1  |     at Function._load (node:internal/modules/cjs/loader:1128:12)
worker-1  |     at TracingChannel.traceSync (node:diagnostics_channel:322:14)
worker-1  |     at wrapModuleLoad (node:internal/modules/cjs/loader:219:24)
worker-1  |     at cjsLoader (node:internal/modules/esm/translators:263:5)
worker-1  |     at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:196:7)
worker-1  | 
worker-1  | Node.js v22.12.0
server-1  | /usr/src/app/node_modules/uws/uws.js:22
server-1  |             throw new Error('This version of uWS.js supports only Node.js LTS versions 16, 18 and 20 on (glibc) Linux, macOS and Windows, on Tier 1 platforms (https://github.com/nodejs/node/blob/master/BUILDING.md#platform-list).\n\n' + e.toString());
server-1  |                   ^
server-1  | 
server-1  | Error: This version of uWS.js supports only Node.js LTS versions 16, 18 and 20 on (glibc) Linux, macOS and Windows, on Tier 1 platforms (https://github.com/nodejs/node/blob/master/BUILDING.md#platform-list).
server-1  | 
server-1  | Error: Cannot find module './uws_linux_x64_127.node'
server-1  | Require stack:
server-1  | - /usr/src/app/node_modules/uws/uws.js
server-1  |     at /usr/src/app/node_modules/uws/uws.js:22:9
server-1  |     at Object.<anonymous> (/usr/src/app/node_modules/uws/uws.js:24:3)
server-1  |     at Module._compile (node:internal/modules/cjs/loader:1565:14)
server-1  |     at Object..js (node:internal/modules/cjs/loader:1708:10)
server-1  |     at Module.load (node:internal/modules/cjs/loader:1318:32)
server-1  |     at Function._load (node:internal/modules/cjs/loader:1128:12)
server-1  |     at TracingChannel.traceSync (node:diagnostics_channel:322:14)
server-1  |     at wrapModuleLoad (node:internal/modules/cjs/loader:219:24)
server-1  |     at cjsLoader (node:internal/modules/esm/translators:263:5)
server-1  |     at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:196:7)
server-1  | 
server-1  | Node.js v22.12.0
worker-1 exited with code 1                                                        
server-1 exited with code 1          

Both server-1 and worker-1 containers crash at build.

Changes

Replaced the moving LTS tag with a pinned Node.js version(v20):

- FROM node:lts-alpine3.19
+ FROM node:20-alpine

Tests

Verified that:

• The server and worker containers now start successfully.
• No runtime errors occur during initialization.