Add GitHub enumeration capabilities (#25)

This adds rudimentary GitHub repository enumeration capabilities to Nosey Parker.

- A new github repos list command is available, which uses the GitHub REST API
  to enumerate repositories belonging to one or more users or organizations.
- The output can be written in textual, JSON, and JSON lines format.
- An optional GitHub personal access token can be supplied, which provides
  a much greater rate limit than with unauthenticated access, and may make
  additional repositories accessible.

Fixes #15.

.github/workflows/rust-clippy.yml

@@ -28,7 +28,7 @@ jobs:
       actions: read # only required for a private repository by github/codeql-action/upload-sarif to get the Action run status
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install system dependencies
         run: |
@@ -41,7 +41,6 @@ jobs:
         with:
           toolchain: stable
           components: clippy
-          override: true
 
       - name: Cache
         uses: actions/cache@v3

.rustfmt.toml

@@ -3,3 +3,4 @@ max_width = 100
 newline_style = "Unix"
 tab_spaces = 4
 fn_call_width = 80
+edition = "2021"

CHANGELOG.md

@@ -8,6 +8,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ## Unreleased
 
 ### Additions
+- Nosey Parker now has rudimentary support for enumerating repositories from GitHub users and organizations.
+  The new `github repos list` command uses the GitHub REST API to enumerate repositories belonging to one or more users or organizations.
+  An optional GitHub Personal Access Token can be provided via the `GITHUB_TOKEN` environment variable.
+
 - Nosey Parker now has an optional `rule_profiling` crate feature that causes performance-related statistics to be collected and reported when scanning.
   This feature imposes some performance cost and is only useful to rule authors, and so is disabled by default.