Adding code coverage (#8)

* Adding Tarpaulin coverage 

* Add coveralls badge

.github/workflows/coverage.yml

@@ -0,0 +1,18 @@
+name: coverage
+
+on: [ push, pull_request ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - name: Push to coveralls.io
+      env:
+        COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
+      run: |
+        cargo install cargo-tarpaulin
+        cargo tarpaulin --ciserver github-ci --coveralls $COVERALLS_REPO_TOKEN

.github/workflows/pre-commit.yaml

@@ -1,9 +1,6 @@
 name: pre-commit
 
-on:
-  pull_request:
-  push:
-    branches: [master, devel]
+on: [ push, pull_request ]
 
 jobs:
   pre-commit:

README.md

@@ -4,6 +4,7 @@
 [![documentation](https://docs.rs/fixed-bigint/badge.svg)](https://docs.rs/fixed-bigint/)
 [![minimum rustc 1.51](https://img.shields.io/badge/rustc-1.51+-red.svg)](https://rust-lang.github.io/rfcs/2495-min-rust-version.html)
 [![build status](https://github.com/kaidokert/fixed-bigint-rs/actions/workflows/rust.yml/badge.svg)](https://github.com/kaidokert/fixed-bigint-rs/actions)
+[![Coverage Status](https://coveralls.io/repos/github/kaidokert/fixed-bigint-rs/badge.svg?branch=main)](https://coveralls.io/github/kaidokert/fixed-bigint-rs?branch=main)
 
 Unsigned BigInt implementation, backed by a fixed-size array.