build(deps): bump signxml from 2.7.3 to 2.8.0 (#87)

Bumps [signxml](https://github.com/kislyuk/signxml) from 2.7.3 to 2.8.0.
- [Release notes](https://github.com/kislyuk/signxml/releases)
- [Changelog](https://github.com/XML-Security/signxml/blob/master/Changes.rst)
- [Commits](https://github.com/kislyuk/signxml/compare/v2.7.3...v2.8.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Pipfile.lock

@@ -54,10 +54,10 @@
         },
         "botocore": {
             "hashes": [
-                "sha256:a5737a5215f9db23344752a4d2a43646c104e6d500a2d6f9409624d2e58c92f1",
-                "sha256:c8b5143e2eaac20ce0d7238fd8ef33f7969139ccd616edb54fd3a482cdfd0e6c"
+                "sha256:cce790e65368d28dfd715558daea6890922716efa69d3a4c76d80348a71ad460",
+                "sha256:e582e3ba61d812e8dd0939c0455c6f68cf41587506a3a30deafc54825087de01"
             ],
-            "version": "==1.17.6"
+            "version": "==1.17.7"
         },
         "celery": {
             "hashes": [
@@ -69,10 +69,10 @@
         },
         "certifi": {
             "hashes": [
-                "sha256:5ad7e9a056d25ffa5082862e36f119f7f7cec6457fa07ee2f8c339814b80c9b1",
-                "sha256:9cd41137dc19af6a5e03b630eefe7d1f458d964d406342dd3edf625839b944cc"
+                "sha256:5930595817496dd21bb8dc35dad090f1c2cd0adfaf21204bf6732ca5d8ee34d3",
+                "sha256:8fc0819f1f30ba15bdb34cceffb9ef04d99f420f68eb75d901e9560b8749fc41"
             ],
-            "version": "==2020.4.5.2"
+            "version": "==2020.6.20"
         },
         "cffi": {
             "hashes": [
@@ -743,11 +743,11 @@
         },
         "signxml": {
             "hashes": [
-                "sha256:3b78b57e374d5517b4eddbbb27519208ccfbedbcabcf47ee322161f53482f174",
-                "sha256:e362b5eedbc785aec9ac1867f790ecf958d9640a95a34400a830350ba5bb1cc2"
+                "sha256:4c996153153c9b1eb7ff40cf624722946f8c2ab059febfa641e54cd59725acd9",
+                "sha256:d116c283f2c940bc2b4edf011330107ba02f197650a4878466987e04142d43b1"
             ],
             "index": "pypi",
-            "version": "==2.7.3"
+            "version": "==2.8.0"
         },
         "six": {
             "hashes": [