webhook: alter regex to account for x509sha1 GODEBUG removal

go1.24 removes the x509sha1 GODEBUG variable, and with it the
support for SHA-1 signed certs. This commit alters the regex
in unit tests to account for that and prep for go1.24.

Signed-off-by: Madhav Jivrajani <[email protected]>

Author: MadhavJivrajani

staging/src/k8s.io/apiserver/pkg/util/webhook/webhook_test.go

@@ -406,14 +406,14 @@ func TestTLSConfig(t *testing.T) {
 			test:       "server cert with SHA1 signature",
 			clientCA:   caCert,
 			serverCert: append(append(sha1ServerCertInter, byte('\n')), caCertInter...), serverKey: serverKey,
-			errRegex:                         "x509: cannot verify signature: insecure algorithm SHA1-RSA \\(temporarily override with GODEBUG=x509sha1=1\\)",
+			errRegex:                         "x509: cannot verify signature: insecure algorithm SHA1-RSA",
 			increaseSHA1SignatureWarnCounter: true,
 		},
 		{
 			test:       "server cert signed by an intermediate CA with SHA1 signature",
 			clientCA:   caCert,
 			serverCert: append(append(serverCertInterSHA1, byte('\n')), caCertInterSHA1...), serverKey: serverKey,
-			errRegex:                         "x509: cannot verify signature: insecure algorithm SHA1-RSA \\(temporarily override with GODEBUG=x509sha1=1\\)",
+			errRegex:                         "x509: cannot verify signature: insecure algorithm SHA1-RSA",
 			increaseSHA1SignatureWarnCounter: true,
 		},
 	}