Include all licenses in SPDX expression and LICENSE file

[musicinmybrain]

Change the SPDX license expression from MIT to
MIT AND Apache-2.0 AND BSD-3-Clause to reflect all of the licenses that apply to the crate’s sources.

Add license text for Apache-2.0 and the BSD-3-Clause license from Go’s time module to LICENSE. Like MIT, both of these licenses require the license text to be distributed with source and/or binaries.

[anakrish]

@musicinmybrain Thanks for fixing this. Curious: Golang's time pkg (https://pkg.go.dev/time) is BSD-3. Where is the Apache-2.0 coming from?

[anakrish]

@unexge, Can you also take a look at this PR? I'm OK with this PR as-is since we should be correct about licenses, but want to understand where Apache 2.0 is coming from.

[musicinmybrain]

@musicinmybrain Thanks for fixing this. Curious: Golang's time pkg (https://pkg.go.dev/time) is BSD-3. Where is the Apache-2.0 coming from?

Within the “source code,” there is src/builtins/time/diff.rs, which says

regorus/src/builtins/time/diff.rs

Line 2 in 5afbd96

// Licensed under the MIT and Apache 2.0 License.

and more clearly identifies Apache-2.0-licensed code from https://github.com/icza/gox between

regorus/src/builtins/time/diff.rs

Lines 13 to 19 in 5afbd96

	// The following implementation of this function is taken
	// from https://github.com/icza/gox licensed under Apache 2.0.
	//
	// For details, see https://stackoverflow.com/a/36531443/1705598
	//
	// Copyright 2021 icza
	// BEGIN REDISTRIBUTION FROM APACHE 2.0 LICENSED PROJECT

and

regorus/src/builtins/time/diff.rs

Line 62 in 5afbd96

// END REDISTRIBUTION FROM APACHE 2.0 LICENSED PROJECT

---

A number of the .rego files in tests/ appear to be Apache-2.0 as well (and these are distributed in the published crates), e.g.,

regorus/tests/kata/data/pod-cm1/policy.rego

Lines 1 to 3 in 5afbd96

	# Copyright (c) 2023 Microsoft Corporation
	#
	# SPDX-License-Identifier: Apache-2.0

[musicinmybrain]

By the way, the Apache-2.0 text in this PR is taken directly from https://www.apache.org/licenses/LICENSE-2.0.txt.

[anakrish]

@musicinmybrain Thanks!