Drop "backport_lzma" library (#80)

The library was added in 2019 with `tags: true` being set,
but never defined any tag in its repository. Thus it never
was available for installation. Due to being archived and
obviously never being used, it is dropped by this commit.

Author: deathaxe

repository.json

@@ -52,20 +52,6 @@
 				}
 			]
 		},
-		{
-			"name": "backports_lzma",
-			"description": "lzma modules for sublime text 2 and 3",
-			"author": "dvhh",
-			"issues": "https://github.com/packagecontrol/backports_lzma/issues",
-			"releases": [
-				{
-					"base": "https://github.com/packagecontrol/backports_lzma",
-					"platforms": ["windows-x32", "windows-x64"],
-					"python_versions": ["3.3"],
-					"tags": true
-				}
-			]
-		},
 		{
 			"name": "backrefs",
 			"description": "Backrefs regular expression wrapper.",