Update MSRV to 1.63

So we can use the I/O safety feature stabilised in 1.63:
rust-lang/rust#95118.

Author: Thomasdezeeuw

.github/workflows/main.yml

@@ -15,14 +15,14 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        build: [stable, 1.46.0, beta, nightly, macos, windows]
+        build: [stable, 1.63.0, beta, nightly, macos, windows]
         include:
           - build: stable
             os: ubuntu-latest
             rust: stable
-          - build: 1.46.0
+          - build: 1.63.0
             os: ubuntu-latest
-            rust: 1.46.0
+            rust: 1.63.0
           - build: beta
             os: ubuntu-latest
             rust: beta

README.md

@@ -66,7 +66,7 @@ feature flag.
 
 # Minimum Supported Rust Version (MSRV)
 
-Socket2 uses 1.46.0 as MSRV.
+Socket2 uses 1.63.0 as MSRV.
 
 # License