test(static-html): Make a replace operation less invasive

The replacement has been introduced for replacing the report creation
timestamp only. However, `replace()` replaces all matches and the
pattern would all so match the timestamp value of issues. So, replace
only the first match, so that issues (with timestamps) can be added in a
following change.

[1]: ba0e4cb

Signed-off-by: Frank Viernau <frank_viernau@epam.com>

plugins/reporters/static-html/src/funTest/kotlin/StaticHtmlReporterFunTest.kt

@@ -54,7 +54,7 @@ class StaticHtmlReporterFunTest : WordSpec({
         "successfully export to a static HTML page" {
             val timeStampPattern = Regex("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(\\.\\d+)?Z")
             val ortResult = readOrtResult("src/funTest/assets/reporter-test-input.yml")
-            val actualReport = generateReport(ortResult).replace(timeStampPattern, "<REPLACE_TIMESTAMP>")
+            val actualReport = generateReport(ortResult).replaceFirst(timeStampPattern, "<REPLACE_TIMESTAMP>")
 
             val expectedReport = matchExpectedResult(
                 getAssetFile("static-html-reporter-test-expected-output.html"),