bump msrv to 1.41.0

Sven Lechner · Sven Lechner · commit cd9a57bad5c4 · 2020-07-13T00:14:48.000+02:00
1.41.0 is the version currently used on Ubuntu LTS releases.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -39,7 +39,7 @@ jobs:
           - stable
           - beta
           - nightly
-          - 1.31.0
+          - 1.41.0
     steps:
       - name: Checkout sources
         uses: actions/checkout@v2
diff --git a/rust-toolchain b/rust-toolchain
@@ -0,0 +1 @@
+1.41.0
