chore: Update .travis.yml - Add Python 3.10 and latest LXML (#185)

- update compatibility matrix with new LXML and Python releases
- excluded LXML version, that does not build on python 3.10.1
- upgrade to Bionic as base distro.
- remove deprecated "sudo" root key

Author: phanak-sap

.travis.yml

@@ -1,11 +1,11 @@
-dist: xenial
-sudo: required
+dist: bionic 
 language: python
 python:
   - "3.6"
   - "3.7"
   - "3.8"
   - "3.9"
+  - "3.10.1"
 
 env:
   - LXML_VERSION=3.7.3
@@ -16,7 +16,8 @@ env:
   - LXML_VERSION=4.3.5
   - LXML_VERSION=4.4.3
   - LXML_VERSION=4.5.2
-  - LXML_VERSION=4.6.3
+  - LXML_VERSION=4.6.5
+  - LXML_VERSION=4.7.1
 
 jobs:
   exclude:
@@ -42,6 +43,23 @@ jobs:
       env: LXML_VERSION=4.1.1      
     - python: 3.9
       env: LXML_VERSION=4.2.6           
+    - python: 3.10.1
+      env: LXML_VERSION=3.7.3
+    - python: 3.10.1
+      env: LXML_VERSION=3.8.0
+    - python: 3.10.1
+      env: LXML_VERSION=4.0.0     
+    - python: 3.10.1
+      env: LXML_VERSION=4.1.1
+    - python: 3.10.1
+      env: LXML_VERSION=4.2.6
+    - python: 3.10.1
+      env: LXML_VERSION=4.3.5
+    - python: 3.10.1
+      env: LXML_VERSION=4.4.3
+    - python: 3.10.1
+      env: LXML_VERSION=4.5.2      
+
 
 # command to install dependencies
 install: