ci(reuse): add reuse compliance workflow

[lfals]

Summary

Implements REUSE compliance pipeline action.

Changes

• Add REUSE CI workflow at .github/workflows/reuse.yml
• Add REUSE.toml with config

Validation

Tested with local run of the action using act

• Command: act -j reuse-compliance-check

Scenarios

• Test with no license header

...

| # SUMMARY
|
| * Bad licenses: 0                                                                                               
| * Deprecated licenses: 0
| * Licenses without file extension: 0
| * Missing licenses: CC0-1.0                                                                                     
| * Unused licenses: 0
| * Used licenses: AGPL-3.0-or-later, CC0-1.0
| * Read errors: 0
| * Invalid SPDX License Expressions: 0                                                                           
| * Files with copyright information: 6 / 132                                                                     
| * Files with license information: 6 / 132
|                                                                                                                 
| Unfortunately, your project is not compliant with version 3.3 of the REUSE Specification :-(
|                                                                                                                 
...                                                                                                           
|
[REUSE Compliance Check/reuse-compliance-check]   ❌  Failure - Main REUSE Compliance Check [1.25852975s]         [REUSE Compliance Check/reuse-compliance-check] exit with `FAILURE`: 1                                            
[REUSE Compliance Check/reuse-compliance-check] ⭐ Run Complete job
[REUSE Compliance Check/reuse-compliance-check]   ✅  Success - Complete job                                      
[REUSE Compliance Check/reuse-compliance-check] 🏁  Job failed

• Test after running reuse download --all

...

| # SUMMARY                                                                                                      
|
| * Bad licenses: 0
| * Deprecated licenses: 0                                                                                        
| * Licenses without file extension: 0
| * Missing licenses: 0
| * Unused licenses: 0
| * Used licenses: AGPL-3.0-or-later, CC0-1.0                                                                     
| * Read errors: 0
| * Invalid SPDX License Expressions: 0
| * Files with copyright information: 6 / 132                                                                     
| * Files with license information: 6 / 132
|                                                                                                                 
| Unfortunately, your project is not compliant with version 3.3 of the REUSE Specification :-(
...                                                                                                                
|
[REUSE Compliance Check/reuse-compliance-check]   ❌  Failure - Main REUSE Compliance Check [1.172589875s]        [REUSE Compliance Check/reuse-compliance-check] exit with `FAILURE`: 1                                            
[REUSE Compliance Check/reuse-compliance-check] ⭐ Run Complete job
[REUSE Compliance Check/reuse-compliance-check]   ✅  Success - Complete job                                      
[REUSE Compliance Check/reuse-compliance-check] 🏁  Job failed

• Test after adding license headers

...
| # SUMMARY
|
| * Bad licenses: 0
| * Deprecated licenses: 0
| * Licenses without file extension: 0
| * Missing licenses: 0
| * Unused licenses: 0
| * Used licenses: AGPL-3.0-or-later, CC0-1.0                                                                     
| * Read errors: 0
| * Invalid SPDX License Expressions: 0                                                                           
| * Files with copyright information: 132 / 132
| * Files with license information: 132 / 132                                                                     
|
| Congratulations! Your project is compliant with version 3.3 of the REUSE Specification :-)
[REUSE Compliance Check/reuse-compliance-check]   ✅  Success - Main REUSE Compliance Check [1.168571208s]        [REUSE Compliance Check/reuse-compliance-check] ⭐ Run Complete job
[REUSE Compliance Check/reuse-compliance-check] Cleaning up container for job reuse-compliance-check
[REUSE Compliance Check/reuse-compliance-check]   ✅  Success - Complete job                                      
[REUSE Compliance Check/reuse-compliance-check] 🏁  Job succeeded

[vitormattos]

Nice!