Add test for server

A test fixture to start the server and a first test case is added.

The fixture tries to assure that the server is installed and running.
If it is not installed the fixture uses pip to install it.

The server and the installation by pip is run bei the same Python
executable that also runs pytest.

The github workflow for pytest is adapted to install akkudoktor-eos.

Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>

tests/test_server.py

@@ -0,0 +1,63 @@
+import requests
+
+
+def test_server(server):
+    """
+    Test the server
+    """
+    result = requests.get(f"{server}/gesamtlast_simple?year_energy=2000&")
+    assert result.status_code == 200
+    assert (
+        result.text
+        == """[
+  0.12399409965368197,
+  0.12082955072761034,
+  0.1186152098599658,
+  0.13282048719613798,
+  0.16801614895243458,
+  0.18833079485066814,
+  0.2060958576163904,
+  0.23815979421159755,
+  0.256794470747979,
+  0.2730286944402595,
+  0.2837831370699189,
+  0.2880791113592318,
+  0.27868845536305187,
+  0.2593976275300202,
+  0.26565341182134644,
+  0.2834322084492842,
+  0.3385133447353511,
+  0.36541124595269503,
+  0.33781770981176945,
+  0.29218838246014817,
+  0.24535542466592053,
+  0.19484917288665324,
+  0.15634028941335018,
+  0.13309410380383394,
+  0.1239736903705896,
+  0.12074280282759843,
+  0.11849705069574769,
+  0.1320224904313182,
+  0.16699106562771282,
+  0.18856343364342354,
+  0.20578134176859084,
+  0.23760516695843145,
+  0.25675411140321175,
+  0.2729442256919556,
+  0.2837782018548114,
+  0.2882881388086184,
+  0.2800061651414149,
+  0.26039842637914645,
+  0.26613497240454587,
+  0.28441116400389416,
+  0.33941195977626437,
+  0.36621100374643395,
+  0.3391062422788601,
+  0.29391186081171267,
+  0.24686897327498972,
+  0.19620626090788126,
+  0.1570820352949701,
+  0.13332596485058107
+]
+"""
+    )