charset: remove dependency on x/net and XML for extracting charset (#669)

Previously we we're dependent on x/net and xml packages. This change
should improve performance.

Author: gabriel-vasile

.github/workflows/benchmark.yml

@@ -20,14 +20,10 @@ jobs:
       with:
         go-version: 'stable'
     - run: go install golang.org/x/perf/cmd/benchstat@latest
-
-    # Hard to get stable results inside github actions, I think because of the shared
-    # nature of the runners. Take the results of this benchmark with a grain of salt.
-    - run: go test -run=none -bench=. -count=10 -timeout=30m ./... > /tmp/prev
-
+    - run: go test -run=none -bench=. -count=10 -benchtime=200ms -timeout=1h ./... > /tmp/prev
     - name: Checkout code
       uses: actions/[email protected]
     # Second run of benchmarks
-    - run: go test -run=none -bench=. -count=10 -timeout=30m ./... > /tmp/curr
+    - run: go test -run=none -bench=. -count=10 -benchtime=200ms -timeout=1h ./... > /tmp/curr
 
     - run: benchstat /tmp/prev /tmp/curr

go.mod

@@ -7,9 +7,7 @@ module github.com/gabriel-vasile/mimetype
 // https://github.com/golang/go/issues/69095
 go 1.23.0
 
-toolchain go1.23.1
-
-require golang.org/x/net v0.39.0
+toolchain go1.23.6
 
 // v1.4.4 had a test file detected as malicious by antivirus software. #575
 retract v1.4.4