Add libjemalloc2 and libtcmalloc-minimal4 to Dockerfile

[n0vad3v]

This PR adds two malloc lib to Dockerfile, which allows user to switch between them:

• LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2 will use jemalloc
• LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libtcmalloc_minimal.so.4.5.6 will use tcmalloc
• If no LD_PRELOAD set, it will use Glibc malloc

version: '3'

services:
  webp:
    image: webpsh/webp-server-go
    restart: always
    environment:
      - MALLOC_ARENA_MAX=1
      #- LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2
      - LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libtcmalloc_minimal.so.4.5.6
    volumes:
      - ./pics:/opt/pics
      - ./exhaust:/opt/exhaust
      - ./config.json:/etc/config.json
    ports:
      -  127.0.0.1:3333:3333

[github-actions]

ghcr.io/webp-sh/webp_server_go (debian 11.7)
============================================
Total: 0 (HIGH: 0, CRITICAL: 0)

[codecov]

Codecov Report

Merging #222 (08a0097) into master (9efead2) will decrease coverage by 3.24%.
The diff coverage is 77.81%.

@@            Coverage Diff             @@
##           master     #222      +/-   ##
==========================================
- Coverage   83.57%   80.34%   -3.24%     
==========================================
  Files           6        6              
  Lines         542      636      +94     
==========================================
+ Hits          453      511      +58     
- Misses         61       85      +24     
- Partials       28       40      +12     

Impacted Files	Coverage Δ
encoder.go	67.03% <68.88%> (-10.11%)	⬇️
helper.go	82.35% <74.60%> (-6.42%)	⬇️
router.go	93.16% <95.00%> (+3.47%)	⬆️
config.go	100.00% <100.00%> (ø)
prefetch.go	100.00% <100.00%> (ø)
webp-server.go	79.20% <100.00%> (+2.03%)	⬆️

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[github-actions]

ghcr.io/webp-sh/webp_server_go (debian 11.7)
============================================
Total: 0 (HIGH: 0, CRITICAL: 0)