Fix and modernize Travis CI

.travis.yml

@@ -1,13 +1,13 @@
 language: python
 python:
-  - "3.4"
-  - "3.5"
-  - "3.6"
-  - "3.7"
-  - "3.8"
+  - 3.6
+  - 3.7
+  - 3.8
+  - 3.9
 install:
-  - "pip install ."
-# command to run tests
-script: py.test
+  - sudo apt-get install libgeos-dev
+  - pip install -r requirements-dev.txt
+  - pip install -r requirements.txt
+script: python -m pytest
 notifications:
   email: false

requirements-dev.txt

@@ -0,0 +1 @@
+pytest>=6.2.0

setup.py

@@ -13,9 +13,10 @@
     keywords=["openstreetmap", "overpass", "wrapper"],
     classifiers=[
         "License :: OSI Approved :: Apache Software License",
-        "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
         "Topic :: Scientific/Engineering :: GIS",
         "Topic :: Utilities",
     ],