Excessively strict swift testcases

[petergardfjall]

There are a couple of pkg:swift test cases that seem excessively strict, since they require an implementation that follows the how-to-parse procedure to reject the purl pkg:swift/github.com/Alamofire/@5.4.3.

An implementation that follows the aforementioned parse procedure would strip the slash before the @ separator as specified in

purl-spec/docs/how-to-parse.md

Lines 59 to 60 in 5d9516c

	- Strip all trailing '/' characters (e.g., '/', '//', '///' and
	so on) from the **remainder**

to end up with namespace: github.com, name: Alamofire.

So either the procedure is wrong or the testcase is overly strict.

The two testcases in question are:

purl-spec/tests/types/swift-test.json

Lines 88 to 105 in 5d9516c

	{
	"description": "invalid swift purl without name",
	"test_group": "base",
	"test_type": "parse",
	"input": "pkg:swift/github.com/Alamofire/@5.4.3",
	"expected_output": null,
	"expected_failure": true,
	"expected_failure_reason": "Should fail to parse a PURL from invalid purl input"
	},
	{
	"description": "invalid swift purl without name",
	"test_group": "base",
	"test_type": "parse",
	"input": "pkg:swift/github.com/Alamofire/@5.4.3",
	"expected_output": null,
	"expected_failure": true,
	"expected_failure_reason": "Should fail to parse a PURL from invalid canonical purl input"
	},

[petergardfjall]

A PR to drop these two testcases was opened in #826.

[petergardfjall]

The PURL spec also says

All leading and trailing slashes '/' are not significant and should be stripped in the canonical form. They are not part of the name.