refactor: migrate from go-git to go-getter

[vmaerten]

🚀 Migration from go-git to go-getter

This PR migrates our codebase from go-git to go-getter for several reasons:

• 🚫 go-git does not support insteadOf by default (Apply .gitconfig insteadOf rules to Repository.clone() go-git/go-git#844)
• 🔖 It does not work with commit or tag, only branches
• 🔐 go-git does not pick up SSH keys by default (ssh private key not being picked up go-git/go-git#218)

As go-getter uses underlying Git, it loads all configuration by default. This is massively used by Terraform and works well.
Using go-getter will open the doors to supporting other remotes like S3 or GCP in the future.

📌 Comparison examples: go-git vs go-getter

🔑 SSH usage

Detail

# https://taskfile.dev

version: '3'
includes:
  app:
    taskfile: [email protected]:go-task/task.git//website/Taskfile.yml

vars:
  GREETING: Hello, World!

tasks:
  default:
    cmds:
      - echo "{{.GREETING}}"
    silent: true

📌 Referencing a specific commit

Detail

# https://taskfile.dev

version: '3'
includes:
  app:
    taskfile: https://github.com/go-task/task.git//website/Taskfile.yml?ref=2b713f564fad541c0c342cf78fe8767e16b7798b

vars:
  GREETING: Hello, World!

tasks:
  default:
    cmds:
      - echo "{{.GREETING}}"
    silent: true

🏷️ Referencing a tag

Detail

# https://taskfile.dev

version: '3'
includes:
  app:
    taskfile: https://github.com/go-task/task.git//website/Taskfile.yml?ref=v3.45.5

vars:
  GREETING: Hello, World!

tasks:
  default:
    cmds:
      - echo "{{.GREETING}}"
    silent: true

I've also added local caching to avoid cloning the same repository multiple times. For example, in a setup where a local Taskfile includes a Git-based Taskfile, which itself includes another Taskfile from the same repository, the repo used to be cloned twice. With the new caching mechanism, it's now cloned only once.