feat: switch license to SPDX

[natanasow]

Description:

Change all license declarations to SPDX format.

Related issue(s):

Fixes #1150

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[github-actions]

Test Results

 17 files  ± 0  103 suites  ±0   25m 58s ⏱️ - 3m 11s
370 tests +20  352 ✅ +26  18 💤 ±0  0 ❌  - 6 
467 runs  ± 0  447 ✅ + 6  20 💤 ±0  0 ❌  - 6 

Results for commit dd647eb. ± Comparison against base commit 31284cc.

This pull request removes 2 and adds 22 tests. Note that renamed tests count towards both.

"before all" hook for "should reject tokens for a single account" ‑ HIP904 TokenRejectContract Test Suite "before all" hook for "should reject tokens for a single account"
"before each" hook for "Should check the existance of a token ID" ‑ @OZERC1155Token Test Suite "before each" hook for "Should check the existance of a token ID"

Should NOT allow a non-operator to transfer tokens to another account ‑ @OZERC1155Token Test Suite Should NOT allow a non-operator to transfer tokens to another account
Should NOT burn insufficient amount of token ‑ @OZERC1155Token Test Suite Should NOT burn insufficient amount of token
Should NOT transfer the ownership to another account if the caller is not owner ‑ @OZERC1155Token Test Suite Should NOT transfer the ownership to another account if the caller is not owner
Should allow an operator to transfer a token to another account ‑ @OZERC1155Token Test Suite Should allow an operator to transfer a token to another account
Should allow an operator to transfer tokens in batch to another account ‑ @OZERC1155Token Test Suite Should allow an operator to transfer tokens in batch to another account
Should burn token in batch ‑ @OZERC1155Token Test Suite Should burn token in batch
Should burn token ‑ @OZERC1155Token Test Suite Should burn token
Should check if an address is another address's operator ‑ @OZERC1155Token Test Suite Should check if an address is another address's operator
Should check the existance of a token ID ‑ @OZERC1155Token Test Suite Should check the existance of a token ID
Should retireve the total supply of a token ID ‑ @OZERC1155Token Test Suite Should retireve the total supply of a token ID
…

♻️ This comment has been updated with latest results.