fix: Relaxing label parsing for Bazel 8 (#2021)

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**What type of PR is this?**

> Uncomment one line below and remove others.
> Bug fix

**What package or component does this PR mostly affect?**

> For example:
> all

**What does this PR do? Why is it needed?**
The label format changed with Bazel 8 and needs to be adapted here

**Which issues(s) does this PR fix?**

Fixes #2019

**Other notes for review**

Author: darkrift

label/label.go

@@ -71,7 +71,7 @@ var NoLabel = Label{}
 var (
 	// This was taken from https://github.com/bazelbuild/bazel/blob/71fb1e4188b01e582a308cfe4bcbf1c730eded1b/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java#L159C1-L164
 	// ~ and + are both allowed as the former is used in canonical repo names by Bazel 7 and earlier and the latter in Bazel 8.
-	labelRepoRegexp = regexp.MustCompile(`^@$|^[A-Za-z0-9_.-][A-Za-z0-9_.~+-]*$`)
+	labelRepoRegexp = regexp.MustCompile(`^@$|^[A-Za-z0-9_.~+-]*$`)
 	// This was taken from https://github.com/bazelbuild/bazel/blob/master/src/main/java/com/google/devtools/build/lib/cmdline/LabelValidator.java
 	// Package names may contain all 7-bit ASCII characters except:
 	// 0-31 (control characters)

label/label_test.go

@@ -91,6 +91,7 @@ func TestParse(t *testing.T) {
 		{str: "@rules_python++pip+name_dep//:_pkg", want: Label{Repo: "rules_python++pip+name_dep", Name: "_pkg"}},
 		{str: "@rules_python++pip+name//:dep_pkg", want: Label{Repo: "rules_python++pip+name", Name: "dep_pkg"}},
 		{str: "@@rules_python++python+python_3_10_x86_64-unknown-linux-gnu//:python_runtimes", want: Label{Repo: "rules_python++python+python_3_10_x86_64-unknown-linux-gnu", Name: "python_runtimes", Canonical: true}},
+		{str: "@@+toolchains+jfrog_linux_amd64//:jfrog_toolchain", want: Label{Repo: "+toolchains+jfrog_linux_amd64", Name: "jfrog_toolchain", Canonical: true}},
 	} {
 		got, err := Parse(tc.str)
 		if err != nil && !tc.wantErr {