DASH: Fix time unit error for disposing. v6.0.138 (#4111)

## Cause
dash auto dispose is configured by seconds, but the code compare by
usecond, 1 second = 1,000,000 useconds.

releated to #4097
Bug introduced after #4097 supported Dash auto dispose after a timeout
without media data.

## How to reproduce

1. `./objs/srs -c conf/dash.conf`
2. publish a rtmp stream.
3. play dash stream. -> no dash stream, always 404 error.

---------

Co-authored-by: winlin <winlinvip@gmail.com>

trunk/doc/CHANGELOG.md

@@ -7,6 +7,7 @@ The changelog for SRS.
 <a name="v6-changes"></a>
 
 ## SRS 6.0 Changelog
+* v6.0, 2024-07-13, Merge [#4111](https://github.com/ossrs/srs/pull/4111): DASH: Fix time unit error for disposing. v6.0.138 (#4111)
 * v6.0, 2024-07-09, Merge [#4028](https://github.com/ossrs/srs/pull/4028): HTTPS: Support config key/cert for HTTPS API. v6.0.137 (#4028)
 * v6.0, 2024-07-09, Merge [#4109](https://github.com/ossrs/srs/pull/4109): UniquePtr: Support SrsUniquePtr to replace SrsAutoFree. v6.0.136 (#4109)
 * v6.0, 2024-07-08, Merge [#4042](https://github.com/ossrs/srs/pull/4042): Refine config directive token parsing. v6.0.135 (#4042)

trunk/src/app/srs_app_config.cpp

@@ -6871,7 +6871,7 @@ srs_utime_t SrsConfig::get_dash_dispose(std::string vhost)
 {
     SRS_OVERWRITE_BY_ENV_SECONDS("srs.vhost.dash.dash_dispose"); // SRS_VHOST_DASH_DASH_DISPOSE
 
-    static srs_utime_t DEFAULT = 120;
+    static srs_utime_t DEFAULT = 120 * SRS_UTIME_SECONDS;
     
     SrsConfDirective* conf = get_dash(vhost);
     if (!conf) {

trunk/src/core/srs_core_version6.hpp

@@ -9,6 +9,6 @@
 
 #define VERSION_MAJOR       6
 #define VERSION_MINOR       0
-#define VERSION_REVISION    137
+#define VERSION_REVISION    138
 
 #endif